Maybe gzip compression (zlib) doesn't belong inside scid.
To remove, apply this patch, and delete the src/zlib directory

Index: configure
===================================================================
--- configure	(revision 1867)
+++ configure	(working copy)
@@ -302,79 +302,9 @@
     return $success
 }
 
-
-# testzlib_sh:
-#    Script used to test if the system has zlib installed.
-#
-set testzlib {#!/bin/sh
-CC=gcc
-cat <<EOF > testzlib.c
-#include <zlib.h>
-int main()
-{
-    z_streamp z;
-    deflateInit(z, 0);
-    return 0;
-}
-EOF
-
-$CC -o testzlib testzlib.c -lz
-if [ -f testzlib ]; then
-    exit 0
-else
-    exit 1
-fi
-}
-
-# systemHasZlib:
-#    Determines if the system has zlib installed. If not, the Zlib
-#    version that comes with Scid will be used.
-#
-proc systemHasZlib {} {
-    set systemHasZlib 0
-    flush stdout
-    if {[catch {open testzlib.sh w} f]} { return 0 }
-    puts $f $::testzlib
-    close $f
-    set result 0
-    if {! [catch {exec sh testzlib.sh} err]} { set result 1 }
-    catch {file delete -force testzlib.sh}
-    catch {file delete -force testzlib.c}
-    catch {file delete -force testzlib}
-    return $result
-}
-
-
-# checkZlib:
-#    Checks whether the system has the zlib compression library installed,
-#    if necessary. 
-#
-proc checkZlib {} {
-    global var
-    if {[string first "DZLIB" $var(SCIDFLAGS)] >= 0} {
-        set var(ZLIB) {}
-        set var(OBJS) {$(SCIDOBJS) $(ZLIBOBJS)}
-        return
-    }
-    puts -nonewline "    Checking if your system already has zlib installed: "
-    flush stdout
-    if {[systemHasZlib]} {
-        puts "yes."
-        set var(ZLIB) {-lz}
-        set var(OBJS) {$(SCIDOBJS)}
-    } else {
-        puts "no."
-        append var(SCIDFLAGS) " -DZLIB"
-        set var(ZLIB) {}
-        set var(OBJS) {$(SCIDOBJS) $(ZLIBOBJS)}
-    }
-}
-
-# writeMakefile:
-#    Creates the Makefile using Makefile.conf and the configured
-#    settings.
+#    Creates the Makefile using Makefile.conf and the configured settings.
 #    Also creates tcl/config.tcl
-#
+
 proc writeMakefile {{type ""}} {
     global var defaultVar
   
@@ -404,8 +334,6 @@
         }
     }
 
-    checkZlib
-
     if {[catch {set from [open "$Makefile_conf" r]}]} {
        puts "Error opening file for reading: $Makefile_conf"
        exit 1
Index: src/mfile.h
===================================================================
--- src/mfile.h	(revision 1867)
+++ src/mfile.h	(working copy)
@@ -15,9 +15,6 @@
 
 // An MFile is a file that can be a regular file, or memory-only with
 // no actual file on any device.
-// In addition, an MFile can decode its contents from a GZip (.gz) file
-// and will hopefully in future also be able to extract the contents of
-// all files in a Zip file, as if they were in one large plain file.
 
 
 #ifndef SCID_MFILE_H
@@ -28,25 +25,17 @@
 #include "error.h"
 
 enum mfileT {
-    MFILE_REGULAR = 0, MFILE_MEMORY, MFILE_GZIP, MFILE_ZIP
+    MFILE_REGULAR = 0, MFILE_MEMORY, MFILE_ZIP
 };
 
 class MFile
 {
   private:
     FILE *      Handle;         // For regular files.
-    gzFile      GzHandle;       // For Gzip files.
     fileModeT   FileMode;
     mfileT      Type;
     char *      FileName;
 
-    // The next few fields are used to improve I/O speed on Gzip files, by
-    // avoiding doing a gzgetc() every character, since the zlib file gzio.c
-    // simply does a (relatively slow) gzread() for each gzgetc().
-    byte *      GzBuffer;
-    int         GzBuffer_Avail;
-    byte *      GzBuffer_Current;
-
     // The next few fields are used for in-memory files.
     uint        Capacity;
     uint        Location;
@@ -56,7 +45,6 @@
     char *      FileBuffer;  // Only for files with unusual buffer size.
 
     void  Extend();
-    int   FillGzBuffer();
 
   public:
     MFile() { Init(); }
@@ -119,9 +107,6 @@
         return (Location >= Capacity);
     case MFILE_REGULAR:
         return feof(Handle);
-    case MFILE_GZIP:
-        if (GzBuffer_Avail > 0) { return 0; }
-        return gzeof(GzHandle);
     default:
         return false;
     }
@@ -138,9 +123,6 @@
         return OK;
     }
     Location++;
-    if (Type == MFILE_GZIP) {
-        return (gzputc(GzHandle, value) == EOF) ? ERROR_FileWrite : OK;
-    }
     return (putc(value, Handle) == EOF) ? ERROR_FileWrite : OK;
 }
 
@@ -156,15 +138,6 @@
         return (int) value;
     }
     Location++;
-    if (Type == MFILE_GZIP) {
-        if (GzBuffer_Avail <= 0) {
-            return FillGzBuffer();
-        }
-        GzBuffer_Avail--;
-        int retval = *GzBuffer_Current;
-        GzBuffer_Current++;
-        return retval;
-    }
     #ifdef __GNUC__
     return getc_unlocked(Handle);
     #else
Index: src/pgnscid.cpp
===================================================================
--- src/pgnscid.cpp	(revision 1867)
+++ src/pgnscid.cpp	(working copy)
@@ -54,9 +54,6 @@
     fprintf (stderr, "      -x: Ignore comments before games.\n");
     fprintf (stderr, "      Database name defaults to the PGN filename ");
     fprintf (stderr, "without the \".pgn\" suffix.\n");
-#ifndef NO_ZLIB
-    fprintf (stderr, "  Note: A Gzip compressed file (e.g. filename.pgn.gz) can be used.\n");
-#endif
     exit(1);
 }
 
@@ -103,11 +100,6 @@
     // Make baseName from pgnName if baseName is not provided:
     if (argsleft == 1) {
         strCopy (baseName, pgnName);
-        // If a gzip file, remove two suffixes, the first being ".gz":
-        const char * lastSuffix = strFileSuffix (baseName);
-        if (lastSuffix != NULL  &&  strEqual (lastSuffix, GZIP_SUFFIX)) {
-            strTrimFileSuffix (baseName);
-        }
         // Trim the ".pgn" suffix:
         strTrimFileSuffix (baseName);
     } else {
Index: src/tkscid.cpp
===================================================================
--- src/tkscid.cpp	(revision 1867)
+++ src/tkscid.cpp	(working copy)
@@ -1140,7 +1140,6 @@
 
     if (suffix == NULL  ||
         (!strEqual (suffix, INDEX_SUFFIX)
-         &&  !strEqual (suffix, GZIP_SUFFIX)
          &&  !strEqual (suffix, PGN_SUFFIX))) {
         // Need to add Index file suffix:
         strAppend (fname, INDEX_SUFFIX);
@@ -1328,7 +1327,7 @@
 
     if (db->idx->VerifyFile (db->nb) != OK) {
         db->idx->CloseIndexFile();
-        return errorResult (ti, "Error: name corruption in index file.\nRun \"scidt -N\" on this database to fix it.");
+        return errorResult (ti, "Error: name corruption in index file.\nTry repairing base with Tools->Maintenance->Repair Base.");
     }
 
     db->numGames = db->idx->GetNumGames();
@@ -9894,12 +9893,12 @@
 sc_info (ClientData cd, Tcl_Interp * ti, int argc, const char ** argv)
 {
     static const char * options [] = {
-        "asserts", "clipbase", "decimal", "fsize", "gzip",
+        "asserts", "clipbase", "decimal", "fsize",
         "html", "limit", "preMoveCmd", "priority", "ratings",
         "suffix", "tb", "validDate", "version", "pocket", "pocket_priority", "logmem", "language", NULL
     };
     enum {
-        INFO_ASSERTS, INFO_CLIPBASE, INFO_DECIMAL, INFO_FSIZE, INFO_GZIP,
+        INFO_ASSERTS, INFO_CLIPBASE, INFO_DECIMAL, INFO_FSIZE,
         INFO_HTML, INFO_LIMIT, INFO_PREMOVECMD, INFO_PRIORITY, INFO_RATINGS,
         INFO_SUFFIX, INFO_TB, INFO_VALIDDATE, INFO_VERSION, INFO_POCKET,
         INFO_POCKET_PRIORITY, INFO_LOGMEM, INFO_LANGUAGE
@@ -9926,15 +9925,6 @@
     case INFO_FSIZE:
         return sc_info_fsize (cd, ti, argc, argv);
 
-    case INFO_GZIP:
-        // Return true if gzip files can be decoded by Scid.
-#ifdef NO_ZLIB
-        return setBoolResult (ti, false);
-#else
-        return setBoolResult (ti, true);
-#endif
-        break;
-
     case INFO_HTML:
         if (argc >= 3) {
             htmlDiagStyle = strGetUnsigned (argv[2]);
@@ -10041,7 +10031,7 @@
 
 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // sc_info_fsize:
-//    Given the name of a .si3, .si, .pgn or .pgn.gz file, this command
+//    Given the name of a .si3, .si, .pgn file, this command
 //    returns the number of games in that file. For large PGN files,
 //    the value returned is only an estimate.
 //    To distinguish estimates from correct sizes, an estimate is
@@ -10055,15 +10045,11 @@
     const char * fname = argv[2];
     const char * lastSuffix = strFileSuffix (fname);
     uint fsize = 0;
-    bool isGzipFile = false;
     bool isEpdFile = false;
     bool isRepFile = false;
 
     if (strAlphaContains (fname, ".epd")) { isEpdFile =  true; }
     if (strAlphaContains (fname, ".sor")) { isRepFile =  true; }
-    if (lastSuffix != NULL  &&  strEqual (lastSuffix, GZIP_SUFFIX)) {
-        isGzipFile = true;
-    }
 
     if (lastSuffix != NULL  &&  strEqual (lastSuffix, OLD_INDEX_SUFFIX)) {
         fsize = rawFileSize (fname);
@@ -10081,11 +10067,7 @@
     // Estimate size for PGN files, by reading the first 64 kb
     // of the file and counting the number of games seen:
 
-    if (isGzipFile) {
-        fsize = gzipFileSize (fname);
-    } else {
-        fsize = rawFileSize (fname);
-    }
+    fsize = rawFileSize (fname);
 
     MFile pgnFile;
     if (pgnFile.Open (fname, FMODE_ReadOnly) != OK) {
Index: src/mfile.cpp
===================================================================
--- src/mfile.cpp	(revision 1867)
+++ src/mfile.cpp	(working copy)
@@ -16,15 +16,10 @@
 #include "mfile.h"
 #include "misc.h"
 
-// GZ_BUFFER_SIZE: number of bytes read from a Gzip file at a time.
-const uint GZ_BUFFER_SIZE = 1024;
-
 void
 MFile::Init ()
 {
     Handle = NULL;
-    GzHandle = NULL;
-    GzBuffer = NULL;
     FileMode = FMODE_Both;
     Type = MFILE_MEMORY;
     Capacity = 0;
@@ -81,12 +76,7 @@
     if (FileMode != FMODE_Both  &&  Location == position) { return OK; }
 
     int result;
-    if (Type == MFILE_GZIP) {
-        result = gzseek (GzHandle, position, 0);
-        GzBuffer_Avail = 0;
-    } else {
-        result = fseek (Handle, position, 0);
-    }
+    result = fseek (Handle, position, 0);
     if (result != 0) { return ERROR_FileSeek; }
     Location = position;
     return OK;
@@ -102,7 +92,7 @@
 errorT
 MFile::Open (const char * name, fileModeT fmode)
 {
-    ASSERT (Handle == NULL  &&  GzHandle == NULL);
+    ASSERT (Handle == NULL);
     const char * modeStr = NULL;
     switch (fmode) {
         case FMODE_ReadOnly:   modeStr = "rb";  break;
@@ -112,25 +102,10 @@
     }
 
     const char * suffix = strFileSuffix (name);
-    if (suffix != NULL  &&  strEqual (suffix, GZIP_SUFFIX)) {
-        // We can only open GZip files read-only for now:
-        if (fmode != FMODE_ReadOnly) {
-            return ERROR_FileOpen;
-        }
-        GzHandle = gzopen (name, "rb");
+    Handle = fopen (name, modeStr);
+    if (Handle == NULL) { return ERROR_FileOpen; }
+    Type = MFILE_REGULAR;
 
-        if (GzHandle == NULL) { return ERROR_FileOpen; }
-        Type = MFILE_GZIP;
-        GzBuffer = new byte [GZ_BUFFER_SIZE];
-
-        GzBuffer_Current = GzBuffer;
-        GzBuffer_Avail = 0;
-    } else {
-        Handle = fopen (name, modeStr);
-        if (Handle == NULL) { return ERROR_FileOpen; }
-        Type = MFILE_REGULAR;
-    }
-
     FileMode = fmode;
     FileName = strDuplicate (name);
     Location = 0;
@@ -140,7 +115,7 @@
 errorT
 MFile::Create (const char * name, fileModeT fmode)
 {
-    ASSERT (Handle == NULL  &&  GzHandle == NULL);
+    ASSERT (Handle == NULL);
     const char * modeStr = NULL;
     switch (fmode) {
         case FMODE_WriteOnly: modeStr = "wb";  break;
@@ -165,16 +140,7 @@
         return OK;
     }
     int result;
-    if (Type == MFILE_GZIP) {
-        if (GzBuffer != NULL) {
-        delete[] GzBuffer;
-            GzBuffer = GzBuffer_Current = NULL;
-            GzBuffer_Avail = 0;
-        }
-        result = gzclose (GzHandle);
-    } else {
-        result = fclose (Handle);
-    }
+    result = fclose (Handle);
 
     if (FileBuffer != NULL) {
         delete[] FileBuffer;
@@ -212,15 +178,6 @@
     }
 
     Location += length;
-    
-    if (Type == MFILE_GZIP) {
-      err = OK;
-      while (length-- > 0 && err == OK) {
-        err = (gzputc(GzHandle, *str) == EOF) ? ERROR_FileWrite : OK;
-        str++;
-      }
-      return err;
-    }
 
     return (fwrite( str, length, 1, Handle) != 1) ? ERROR_FileWrite : OK;
 }
@@ -352,17 +309,6 @@
     return result;
 }
 
-int
-MFile::FillGzBuffer ()
-{
-    ASSERT (Type == MFILE_GZIP  &&  GzBuffer != NULL  &&  GzBuffer_Avail <= 0);
-    int bytesread = gzread (GzHandle, GzBuffer, GZ_BUFFER_SIZE);
-    if (bytesread <= 0) { return EOF; }
-    GzBuffer_Avail = bytesread - 1;
-    GzBuffer_Current = &(GzBuffer[1]);
-    return GzBuffer[0];
-    
-}
 
 //////////////////////////////////////////////////////////////////////
 //  End of file: mfile.cpp
Index: src/common.h
===================================================================
--- src/common.h	(revision 1867)
+++ src/common.h	(working copy)
@@ -34,18 +34,6 @@
 #define snprintf _snprintf
 #endif
 
-#ifndef POCKETENGINE
-// Include the zlib header file if it is being compiled with Scid:
-#ifndef NO_ZLIB
-#  ifdef ZLIB
-#    include "zlib/zlib.h"
-#   else
-#    include <zlib.h>
-#  endif
-#endif
-#else
-#define ASSERT(f)
-#endif
 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // CONSTANTS:
 
@@ -76,22 +64,6 @@
 const char PGN_SUFFIX[] = ".pgn";
 
 
-// If the zlib compression library is NOT used, create dummy inline
-// functions to replace those used in zlib, which saves wrapping every
-// zlib function call with #ifndef conditions.
-
-#ifdef NO_ZLIB
-typedef void * gzFile;
-inline gzFile gzopen (const char * name, const char * mode) { return NULL; }
-inline int gzputc (gzFile fp, int c) { return c; }
-inline int gzgetc (gzFile fp) { return -1; }
-inline int gzread (gzFile fp, char * buffer, int length) { return 0; }
-inline int gzeof (gzFile fp) { return 1; }
-inline int gzseek (gzFile fp, int offset, int where) { return 0; }
-inline int gzclose (gzFile fp) { return 0; }
-#endif
-
-
 // Bit Manipulations
 
 #define BIT_7(x)            ((x) & 128)
Index: Makefile.conf
===================================================================
--- Makefile.conf	(revision 1867)
+++ Makefile.conf	(working copy)
@@ -1,4 +1,4 @@
-! Makefile.conf
+!+ Makefile.conf
 !    Makefile template for Scid for Unix operating systems.
 !
 ! This file is NOT an actual Makefile; it is a template file used by 
@@ -49,9 +49,6 @@
 TB = @TB@
 
 ### SCIDFLAGS: Scid customization flags.
-#      Use -DZLIB if your system does not have zlib and you need
-#      to include the code in the src/zlib directory.
-#      The default is to use the system zlib library.
 
 SCIDFLAGS = @SCIDFLAGS@
 
@@ -108,21 +105,8 @@
       src/polyglot/parse.o src/polyglot/pgn.o src/polyglot/piece.o src/polyglot/random.o \
       src/polyglot/san.o src/polyglot/search.o src/polyglot/square.o src/polyglot/util.o
 
-### ZLIBOBJS: object files in the zlib compression library.
+### OBJS: Will be "$(SCIDOBJS)", "$(POLYGLOTOBJS)"
 
-ZLIBOBJS= src/zlib/adler32.o src/zlib/compress.o src/zlib/crc32.o \
-      src/zlib/gzio.o src/zlib/uncompr.o src/zlib/deflate.o src/zlib/trees.o \
-      src/zlib/zutil.o src/zlib/inflate.o src/zlib/infblock.o \
-      src/zlib/inftrees.o src/zlib/infcodes.o src/zlib/infutil.o \
-      src/zlib/inffast.o
-       
-### ZLIB: Should be "-lz" if your system has zlib, "" otherwise.
-
-ZLIB = @ZLIB@
-
-### OBJS: Will be "$(SCIDOBJS)", "$(POLYGLOTOBJS)", and also "$(ZLIBOBJS)" if they are
-#      needed on your system.
-
 OBJS= @OBJS@
 
 ### TCLS: all the .tcl files that make up "scid".
@@ -286,7 +270,7 @@
 	-rm -f $(SHAREDIR)/scid.eco
 
 clean:
-	rm -f game.* tkscid.so tkscid.dll position.* src/*.o src/zlib/*.o src/zlib/*.a src/polyglot/*.o $(EXECS) scid $(SCRIPTS)
+	rm -f game.* tkscid.so tkscid.dll position.* src/*.o src/polyglot/*.o $(EXECS) scid $(SCRIPTS)
 	cd engines/phalanx/ && make clean && cd ../../
 	cd engines/toga/src/ && make clean && cd ../../../
 	cd src/tkdnd/ && make clean && cd ../..
@@ -370,34 +354,34 @@
 scmerge: src/scmerge.o src/misc.o src/index.o src/date.o src/namebase.o \
          src/gfile.o src/bytebuf.o src/textbuf.o src/myassert.o \
          src/stralloc.o src/position.o
-	$(LINK) $(LDFLAGS) -o scmerge src/scmerge.o $(OBJS) $(ZLIB)
+	$(LINK) $(LDFLAGS) -o scmerge src/scmerge.o $(OBJS)
 
 pgnscid: src/pgnscid.o $(OBJS)
-	$(LINK) $(LDFLAGS) -o pgnscid src/pgnscid.o $(OBJS) $(ZLIB)
+	$(LINK) $(LDFLAGS) -o pgnscid src/pgnscid.o $(OBJS)
 
 scidlet: src/scidlet.o src/engine.o src/recog.o src/misc.o src/position.o \
          src/dstring.o src/movelist.o src/myassert.o
 	$(LINK) $(LDFLAGS) -o scidlet src/scidlet.o src/engine.o src/recog.o src/misc.o src/position.o src/movelist.o src/dstring.o src/myassert.o
 
 scidt: src/scidt.o $(OBJS)
-	$(LINK) $(LDFLAGS) -o scidt src/scidt.o $(OBJS) $(ZLIB)
+	$(LINK) $(LDFLAGS) -o scidt src/scidt.o $(OBJS)
 
 tkscid: src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o \
         src/probe.o src/optable.o src/engine.o src/recog.o src/tkdnd/TkDND_XDND.o src/tk_selection.o
 	$(LINK) $(LDFLAGS) -o tkscid src/tkscid.o $(OBJS) src/tree.o \
         src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o \
-        src/engine.o src/recog.o src/tkdnd/TkDND_XDND.o src/tk_selection.o $(ZLIB) $(TK_LIBRARY)
+        src/engine.o src/recog.o src/tkdnd/TkDND_XDND.o src/tk_selection.o $(TK_LIBRARY)
 
 tcscid: src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o \
         src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o
 	$(LINK) $(LDFLAGS) -o tcscid src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o \
-        src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(ZLIB) $(TCL_LIBRARY)
+        src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(TCL_LIBRARY)
 
 # eco2epd is now optional extra program NOT compiled by default, since
 # scid now reads the .eco file format directly.
 
 eco2epd: src/eco2epd.o $(OBJS) src/pbook.o
-	$(LINK) $(LDFLAGS) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o $(ZLIB)
+	$(LINK) $(LDFLAGS) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o
 
 ### Rules to create .o files from .cpp files:
 
@@ -417,11 +401,6 @@
 %.o: %.cpp
 	$(CXX) $(CXXFLAGS) $(TCL_INCLUDE) -o $@ -c $<
 
-### Rule for compiling zlib source files:
-
-src/zlib/%.o: src/zlib/%.c
-	$(CC) $(CFLAGS) -o $@ -c $<
-
 src/tkdnd/TkDND_XDND.o: src/tkdnd/unix/TkDND_XDND.c
 	$(MAKE) -C src/tkdnd/ -f Makefile CC="$(CC)" LINK="$(LINK)" CFLAGS="$(CFLAGS)" \
 	       LDFLAGS="$(LDFLAGS)" TCL_VERSION="$(TCL_VERSION)" TCL_INCLUDE="$(TCL_INCLUDE)" \
Index: COPYING
===================================================================
--- COPYING	(revision 1867)
+++ COPYING	(working copy)
@@ -10,9 +10,8 @@
 
 The only files in Scid NOT distributed under the GPL (since they have
 a different author and copyright, but they are freely distributable)
-are the Zlib library (see the src/zlib directory), a Tcl package
-for sending email using SMTP (see the tcl/ezsmtp directory), and
-endgame tablebase decoding source code (see the src/egtb directory).
+are a Tcl package for sending email using SMTP (see the tcl/ezsmtp directory),
+and endgame tablebase decoding source code (see the src/egtb directory)
 
 Please note: although there is no explicit copyright notice in the
 tablebase decoding code, all rights are reserved by its author
Index: tcl/file/epd.tcl
===================================================================
--- tcl/file/epd.tcl	(revision 1867)
+++ tcl/file/epd.tcl	(working copy)
@@ -108,9 +108,6 @@
   }
   set new_types { {"EPD files" {".epd"} } }
   set open_types $new_types
-  if {[sc_info gzip]} {
-    set open_types { {"EPD files" {".epd" ".epd.gz"} } }
-  }
   if {$fname == ""} {
     if {$cmd == "create"} {
       set fname [tk_getSaveFile -initialdir $::initialDir(epd) -filetypes $new_types -title "Create an EPD file"]
Index: tcl/windows/eco.tcl
===================================================================
--- tcl/windows/eco.tcl	(revision 1867)
+++ tcl/windows/eco.tcl	(working copy)
@@ -282,9 +282,6 @@
   global ecoFile
 
   set ftype { { "Scid ECO files" {".eco"} } }
-  if {[sc_info gzip]} {
-    set ftype { { "Scid ECO files" {".eco" ".eco.gz"} } }
-  }
   set fullname [tk_getOpenFile -initialdir [pwd] -filetypes $ftype -title "Load ECO file"]
   if {[string compare $fullname ""]} {
     if {[catch {sc_eco read $fullname} result]} {
Index: tcl/tools/import.tcl
===================================================================
--- tcl/tools/import.tcl	(revision 1867)
+++ tcl/tools/import.tcl	(working copy)
@@ -251,18 +251,10 @@
     tk_messageBox -type ok -icon error -title "Scid: Error" -message $err
     return
   }
-  if {[sc_info gzip]} {
-    set ftypes {
-      { "Portable Game Notation files" {".pgn" ".PGN" ".pgn.gz"} }
-      { "Text files" {".txt" ".TXT"} }
-      { "All files" {"*"} }
-    }
-  } else {
-    set ftypes {
-      { "Portable Game Notation files" {".pgn" ".PGN"} }
-      { "Text files" {".txt" ".TXT"} }
-      { "All files" {"*"} }
-    }
+  set ftypes {
+    { "Portable Game Notation files" {".pgn" ".PGN"} }
+    { "Text files" {".txt" ".TXT"} }
+    { "All files" {"*"} }
   }
   set fnames [tk_getOpenFile -multiple 1 -initialdir $::initialDir(pgn) -filetypes $ftypes -title "Import from PGN files" ]
   if {$fnames == ""} { return }
Index: tcl/file.tcl
===================================================================
--- tcl/file.tcl	(revision 1867)
+++ tcl/file.tcl	(working copy)
@@ -132,20 +132,11 @@
     return
   }
 
-  if {[sc_info gzip]} {
-    set ftype {
-      { {All Scid files} {.si4 .si3 .pgn .PGN .pgn.gz .epd .epd.gz} }
-      { {Scid databases} {.si4 .si3} }
-      { {PGN files} {.pgn .PGN .pgn.gz} }
-      { {EPD files} {.epd .EPD .epd.gz} }
-    }
-  } else {
-    set ftype {
-      { {All Scid files} {.si4 .si3 .pgn .PGN .epd} }
-      { {Scid databases} {.si4 .si3} }
-      { {PGN files} {.pgn .PGN} }
-      { {EPD files} {.epd .EPD} }
-    }
+  set ftype {
+    { {All Scid files} {.si4 .si3 .pgn .PGN .epd} }
+    { {Scid databases} {.si4 .si3} }
+    { {PGN files} {.pgn .PGN} }
+    { {EPD files} {.epd .EPD} }
   }
   if {$fName == ""} {
     if {! [file isdirectory $::file::finder::data(dir)] } {
@@ -546,18 +537,10 @@
   }
 
   if {$fName == ""} {
-    if {[sc_info gzip]} {
-      set ftype {
-        { "Scid databases, PGN files" {".si4" ".si3" ".pgn" ".PGN" ".pgn.gz"} }
-        { "Scid databases" {".si4" ".si3"} }
-        { "PGN files" {".pgn" ".PGN" ".pgn.gz"} }
-      }
-    } else {
-      set ftype {
-        { "Scid databases, PGN files" {".si4" ".si3" ".pgn" ".PGN"} }
-        { "Scid databases" {".si4" ".si3"} }
-        { "PGN files" {".pgn" ".PGN"} }
-      }
+    set ftype {
+      { "Scid databases, PGN files" {".si4" ".si3" ".pgn" ".PGN"} }
+      { "Scid databases" {".si4" ".si3"} }
+      { "PGN files" {".pgn" ".PGN"} }
     }
     if {! [file isdirectory $::initialDir(base)] } {
       set ::initialDir(base) $::env(HOME)
Index: Makefile.conf.darwin
===================================================================
--- Makefile.conf.darwin	(revision 1867)
+++ Makefile.conf.darwin	(working copy)
@@ -48,9 +48,6 @@
 TB = @TB@
 
 ### SCIDFLAGS: Scid customization flags.
-#      Use -DZLIB if your system does not have zlib and you need
-#      to include the code in the src/zlib directory.
-#      The default is to use the system zlib library.
 
 SCIDFLAGS = @SCIDFLAGS@
 
@@ -106,21 +103,8 @@
       src/polyglot/parse.o src/polyglot/pgn.o src/polyglot/piece.o src/polyglot/random.o \
       src/polyglot/san.o src/polyglot/search.o src/polyglot/square.o src/polyglot/util.o
 
-### ZLIBOBJS: object files in the zlib compression library.
+### OBJS: Will be "$(SCIDOBJS)", "$(POLYGLOTOBJS)"
 
-ZLIBOBJS= src/zlib/adler32.o src/zlib/compress.o src/zlib/crc32.o \
-      src/zlib/gzio.o src/zlib/uncompr.o src/zlib/deflate.o src/zlib/trees.o \
-      src/zlib/zutil.o src/zlib/inflate.o src/zlib/infblock.o \
-      src/zlib/inftrees.o src/zlib/infcodes.o src/zlib/infutil.o \
-      src/zlib/inffast.o
-       
-### ZLIB: Should be "-lz" if your system has zlib, "" otherwise.
-
-ZLIB = @ZLIB@
-
-### OBJS: Will be "$(SCIDOBJS)", "$(POLYGLOTOBJS)", and also "$(ZLIBOBJS)" if they are
-#      needed on your system.
-
 OBJS= @OBJS@
 
 ### TCLS: all the .tcl files that make up "scid".
@@ -242,7 +226,7 @@
 	rm -rf ./dist
 
 clean:
-	rm -f game.* tkscid.so position.* src/*.o src/zlib/*.o src/zlib/*.a src/polyglot/*.o $(EXECS) scid $(SCRIPTS)
+	rm -f game.* tkscid.so position.* src/*.o src/polyglot/*.o $(EXECS) scid $(SCRIPTS)
 	cd engines/phalanx/ && make clean && cd ../../
 	cd engines/toga/src/ && make clean && cd ../../../
 
@@ -379,30 +363,30 @@
 scmerge: src/scmerge.o src/misc.o src/index.o src/date.o src/namebase.o \
           src/gfile.o src/bytebuf.o src/textbuf.o src/myassert.o \
           src/stralloc.o src/position.o
-	$(LINK) $(LDFLAGS) -o scmerge src/scmerge.o $(OBJS) $(ZLIB)
+	$(LINK) $(LDFLAGS) -o scmerge src/scmerge.o $(OBJS)
 
 pgnscid: src/pgnscid.o $(OBJS)
-	$(LINK) $(LDFLAGS) -o pgnscid src/pgnscid.o $(OBJS) $(ZLIB) $(TCL_LIBRARY)
+	$(LINK) $(LDFLAGS) -o pgnscid src/pgnscid.o $(OBJS) $(TCL_LIBRARY)
 
 scidlet: src/scidlet.o src/engine.o src/recog.o src/misc.o src/position.o \
           src/dstring.o src/movelist.o src/myassert.o
 	$(LINK) $(LDFLAGS) -o scidlet src/scidlet.o src/engine.o src/recog.o src/misc.o src/position.o src/movelist.o src/dstring.o src/myassert.o $(TCL_LIBRARY)
 
 scidt: src/scidt.o $(OBJS)
-	$(LINK) $(LDFLAGS) -o scidt src/scidt.o $(OBJS) $(ZLIB) $(TCL_LIBRARY)
+	$(LINK) $(LDFLAGS) -o scidt src/scidt.o $(OBJS) $(TCL_LIBRARY)
 
 tkscid: src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o \
           src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o
-	$(LINK) $(LDFLAGS) -o tkscid src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(ZLIB) $(TK_LIBRARY)
+	$(LINK) $(LDFLAGS) -o tkscid src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(TK_LIBRARY)
 
 tcscid: src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o \
           src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o
-	$(LINK) $(LDFLAGS) -o tcscid src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(ZLIB) $(TCL_LIBRARY)
+	$(LINK) $(LDFLAGS) -o tcscid src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(TCL_LIBRARY)
 
 # eco2epd is now optional extra program NOT compiled by default, since
 # scid now reads the .eco file format directly.
 eco2epd: src/eco2epd.o $(OBJS) src/pbook.o
-	$(LINK) $(LDFLAGS) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o $(ZLIB)
+	$(LINK) $(LDFLAGS) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o
 
 ### Rules to create .o files from .cpp files:
 
@@ -422,9 +406,4 @@
 %.o: %.cpp
 	$(CXX) $(CXXFLAGS) $(TCL_INCLUDE) -o $@ -c $<
 
-### Rule for compiling zlib source files:
-
-src/zlib/%.o: src/zlib/%.c
-	$(CC) $(CFLAGS) -o $@ -c $<
-
 ### End of Makefile
Index: Makefile.vc
===================================================================
--- Makefile.vc	(revision 1867)
+++ Makefile.vc	(working copy)
@@ -140,11 +140,8 @@
 DND_LIBS	= $(DND_LIBS_DIR)\user32.lib $(DND_LIBS_DIR)\shell32.lib $(DND_LIBS_DIR)\ole32.lib 
 
 ##	SCID_FLAGS: Scid customization flags.
-#	Use -DZLIB if your system does not have zlib and you need
-#	to include the code in the src/zlib directory.
-#	The default is to use the system zlib library.
 
-SCID_FLAGS	= -DZLIB
+SCID_FLAGS	=
 
 ##	SCID_TB: Tablebase support.
 #	for no tablebase reading capability.
@@ -173,24 +170,6 @@
 	tcscid.exe
 #	tkscid.exe (unused)
 
-##	ZLIB_OBJS: obj. files in the zlib compression library.
-
-ZLIB_OBJS = \
-	$(TMP_DIR)\adler32.obj \
-	$(TMP_DIR)\compress.obj \
-	$(TMP_DIR)\crc32.obj \
-	$(TMP_DIR)\gzio.obj \
-	$(TMP_DIR)\uncompr.obj \
-	$(TMP_DIR)\deflate.obj \
-	$(TMP_DIR)\trees.obj \
-	$(TMP_DIR)\zutil.obj \
-	$(TMP_DIR)\inflate.obj \
-	$(TMP_DIR)\infblock.obj \
-	$(TMP_DIR)\inftrees.obj \
-	$(TMP_DIR)\infcodes.obj \
-	$(TMP_DIR)\infutil.obj \
-	$(TMP_DIR)\inffast.obj
-
 POL_OBJS = \
       $(TMP_DIR)\pol\attack.obj \
       $(TMP_DIR)\pol\board.obj \
@@ -223,7 +202,6 @@
 #	files that most of the Scid programs use.
 
 SCID_OBJS= \
-      $(ZLIB_OBJS) \
       $(POL_OBJS) \
       $(TMP_DIR)\misc.obj \
       $(TMP_DIR)\index.obj \
@@ -448,9 +426,6 @@
 {src\egtb}.c{$(TMP_DIR)}.obj:
 	$(CC) $(CFLAGS) -Fo$(TMP_DIR)\ $<
 
-{src\zlib}.c{$(TMP_DIR)}.obj:
-	$(CC) $(CFLAGS) -Fo$(TMP_DIR)\ $<
-	
 .rc{$(TMP_DIR)}.res:
 	$(RC) -r -Fo$(TMP_DIR)\$(@B).res $<
 
Index: Makefile.mingwx
===================================================================
--- Makefile.mingwx	(revision 1867)
+++ Makefile.mingwx	(working copy)
@@ -39,11 +39,8 @@
 TB = -DSCID_USE_TB -DT41_INCLUDE
 
 ### SCIDFLAGS: Scid customization flags.
-#      Use -DZLIB if your system does not have zlib and you need
-#      to include the code in the src/zlib directory.
-#      The default is to use the system zlib library.
 
-SCIDFLAGS = -DZLIB
+SCIDFLAGS =
 
 WARNINGS = -Wall
 
@@ -71,17 +68,9 @@
       src/polyglot/parse.o src/polyglot/pgn.o src/polyglot/piece.o src/polyglot/random.o \
       src/polyglot/san.o src/polyglot/search.o src/polyglot/square.o src/polyglot/util.o
 
-### ZLIBOBJS: object files in the zlib compression library.
-
-ZLIBOBJS= src/zlib/adler32.o src/zlib/compress.o src/zlib/crc32.o \
-      src/zlib/gzio.o src/zlib/uncompr.o src/zlib/deflate.o src/zlib/trees.o \
-      src/zlib/zutil.o src/zlib/inflate.o src/zlib/infblock.o \
-      src/zlib/inftrees.o src/zlib/infcodes.o src/zlib/infutil.o \
-      src/zlib/inffast.o
-
 ### OBJS: all standard object files for scid.
 
-OBJS= $(SCIDOBJS) $(ZLIBOBJS)
+OBJS= $(SCIDOBJS)
 
 LANGUAGES = tcl/lang/czech.tcl tcl/lang/deutsch.tcl tcl/lang/francais.tcl tcl/lang/greek.tcl tcl/lang/hungary.tcl tcl/lang/italian.tcl tcl/lang/norsk.tcl tcl/lang/polish.tcl tcl/lang/portbr.tcl tcl/lang/nederlan.tcl tcl/lang/spanish.tcl tcl/lang/serbian.tcl tcl/lang/swedish.tcl
 
@@ -172,7 +161,7 @@
 	$(RC) -O coff scid.rc scid.coff
 
 clean:
-	rm -f src/*.o src/zlib/*.o src/polyglot/*.o $(EXECS) scid.gui scid.coff
+	rm -f src/*.o src/polyglot/*.o $(EXECS) scid.gui scid.coff
 	$(MAKE) -C src/tkdnd/ -f Makefile.mingwx clean
 
 strip:
Index: Makefile.mingw
===================================================================
--- Makefile.mingw	(revision 1867)
+++ Makefile.mingw	(working copy)
@@ -55,13 +55,13 @@
 LFLAGS = $(PROFILE)
 
 ### CPPFLAGS: C++ compiler flags
-CPPFLAGS = -DZLIB $(OPT) $(CPPOPT) $(PROFILE) $(WARNINGS)
+CPPFLAGS = $(OPT) $(CPPOPT) $(PROFILE) $(WARNINGS)
 
 ### CPPFLAGSNOWARN: C++ compiler flags without warnings
-CPPFLAGSNOWARN = -DZLIB $(OPT) $(CPPOPT) $(PROFILE)
+CPPFLAGSNOWARN = $(OPT) $(CPPOPT) $(PROFILE)
 
 ### CFLAGS: C (not C++) compiler flags
-CFLAGS = -DZLIB $(OPT) $(PROFILE)
+CFLAGS = $(OPT) $(PROFILE)
 
 
 ### EXECS: all the evecutable programs compiled from C++ files.
@@ -84,18 +84,8 @@
       src\polyglot\san.o src\polyglot\search.o src\polyglot\square.o src\polyglot\util.o
 
 
-### ZLIBOBJS: object files in the zlib compression library.
-###
-ZLIBOBJS= src\zlib\adler32.obj src\zlib\compress.obj src\zlib\crc32.obj \
-      src\zlib\gzio.obj src\zlib\uncompr.obj src\zlib\deflate.obj \
-      src\zlib\trees.obj src\zlib\zutil.obj src\zlib\inflate.obj \
-      src\zlib\infblock.obj src\zlib\inftrees.obj src\zlib\infcodes.obj \
-      src\zlib\infutil.obj src\zlib\inffast.obj
+OBJS= $(SCIDOBJS)
 
-### OBJS: all standard object files for scid.
-###
-OBJS= $(SCIDOBJS) $(ZLIBOBJS)
-
 ### LANGUAGES: all the extra language files for scid.
 LANGUAGES = tcl\lang\deutsch.tcl tcl\lang\francais.tcl tcl\lang\italian.tcl
       tcl\lang\nederlan.tcl tcl\lang\spanish.tcl tcl\lang\portbr.tcl tcl\lang\swedish.tcl \
@@ -199,7 +189,7 @@
 
 ### To remove object and executable files: type "make clean"
 clean:
-	-del src\*.obj src\zlib\*.obj $(EXECS) scid.gui
+	-del src\*.obj $(EXECS) scid.gui
 
 
 src\tcscid.obj: src\tkscid.cpp
Index: Makefile.cygwin
===================================================================
--- Makefile.cygwin	(revision 1867)
+++ Makefile.cygwin	(working copy)
@@ -49,12 +49,9 @@
 TB = -DSCID_USE_TB
 
 ### SCIDFLAGS: Scid customization flags.
-#      Use -DZLIB if your system does not have zlib and you need
-#      to include the code in the src/zlib directory.
-#      The default is to use the system zlib library.
-#
-SCIDFLAGS =  -DZLIB
 
+SCIDFLAGS =
+
 ### OPTIMIZE: Optimization options for C++ compiler.
 #      -O4 is the most optimization for g++. I have found -O2 to do
 #      just as well, but someone reported a noticable difference in speed
@@ -83,10 +80,6 @@
 #
 CPP_FLAGS = $(PROFILE) $(OPTIMIZE) $(WARNINGS) $(DEBUG) $(SCIDFLAGS)
 
-### CFLAGS: Flags for C compilation (only used for compiling zlib).
-#
-CFLAGS = -O2 -Wall $(PROFILE)
-
 ### LANGUAGES: List of additional Tcl files to include in Scid for
 #       multi-language menu support.
 #       By default, it is all the contributed languages, but you
@@ -118,21 +111,10 @@
       src/myassert.o src/stralloc.o src/mfile.o src/dstring.o src/pgnparse.o \
       src/stored.o src/movelist.o
 
-### ZLIBOBJS: object files in the zlib compression library.
-#
-ZLIBOBJS= src/zlib/adler32.o src/zlib/compress.o src/zlib/crc32.o \
-      src/zlib/gzio.o src/zlib/uncompr.o src/zlib/deflate.o src/zlib/trees.o \
-      src/zlib/zutil.o src/zlib/inflate.o src/zlib/infblock.o \
-      src/zlib/inftrees.o src/zlib/infcodes.o src/zlib/infutil.o \
-      src/zlib/inffast.o
 
-### ZLIB: Should be "-lz" if your system has zlib, "" otherwise.
-#
-ZLIB = 
+### OBJS: Will be "$(SCIDOBJS)"
 
-### OBJS: Will be "$(SCIDOBJS)", and also "$(ZLIBOBJS)" if they are
-#      needed on your system.
-OBJS= $(SCIDOBJS) $(ZLIBOBJS)
+OBJS= $(SCIDOBJS)
 
 ### TCLS: all the .tcl files that make up "scid".
 #
@@ -212,7 +194,7 @@
 ### To remove object and executable files: type "make clean".
 #
 clean:
-	rm -f src/*.o src/zlib/*.o $(EXECS) scid $(SCRIPTS)
+	rm -f src/*.o $(EXECS) scid $(SCRIPTS)
 
 ### To make the executable files smaller: type "make strip".
 #
@@ -284,10 +266,10 @@
 scmerge.exe: src/scmerge.o src/misc.o src/index.o src/date.o src/namebase.o \
 	  src/gfile.o src/bytebuf.o src/textbuf.o src/myassert.o \
 	  src/stralloc.o
-	$(LINK) -o $@ src/scmerge.o $(OBJS) $(ZLIB)
+	$(LINK) -o $@ src/scmerge.o $(OBJS)
 
 pgnscid.exe: src/pgnscid.o $(OBJS)
-	$(LINK) $(PROFILE) -o $@ src/pgnscid.o $(OBJS) $(ZLIB)
+	$(LINK) $(PROFILE) -o $@ src/pgnscid.o $(OBJS)
 
 scidlet.exe: src/scidlet.o src/engine.o src/recog.o src/misc.o src/position.o \
           src/dstring.o src/movelist.o src/myassert.o
@@ -295,20 +277,20 @@
 
 
 scidt.exe: src/scidt.o $(OBJS)
-	$(LINK) -o $@ src/scidt.o $(OBJS) $(ZLIB)
+	$(LINK) -o $@ src/scidt.o $(OBJS)
 
 tkscid.exe: src/tkscid.o $(OBJS) src/tree.o src/filter.o \
 	 src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o
-	$(LINK) -o $@ src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(ZLIB) $(TK_LIBRARY)
+	$(LINK) -o $@ src/tkscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(TK_LIBRARY)
 
 tcscid.exe: src/tcscid.o $(OBJS) src/tree.o src/filter.o \
 	  src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o
-	$(LINK) -o tcscid src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(ZLIB) $(TCL_LIBRARY)
+	$(LINK) -o tcscid src/tcscid.o $(OBJS) src/tree.o src/filter.o src/pbook.o src/crosstab.o src/spellchk.o src/probe.o src/optable.o src/engine.o src/recog.o $(TCL_LIBRARY)
 
 # eco2epd is now optional extra program NOT compiled by default, since
 # scid now reads the .eco file format directly.
 eco2epd: src/eco2epd.o $(OBJS) src/pbook.o
-	$(LINK) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o $(ZLIB)
+	$(LINK) -o eco2epd src/eco2epd.o $(OBJS) src/pbook.o
 
 ### Rules to create .o files from .cpp files:
 #
@@ -329,9 +311,4 @@
 %.o: %.cpp
 	$(COMPILE) $(CPP_FLAGS) -o $@ -c $<
 
-### Rule for compiling zlib source files:
-#
-src/zlib/%.o: src/zlib/%.c
-	$(CC) $(CFLAGS) -o $@ -c $<
-
 ### End of Makefile
