- error checking for unalf -n (dup option, bad #, wildcards)

- maybe: alf foo.alf unix.filename=ATARI.NAM  ...unalf could use this too.

- fuzz alf and unalf with afl++ or similar. this is a work in progress,
  fuzzing takes a long time.

- clean up crunch.c.

- write a formal spec of the alf compression stream format?