tyrutils-ericw is a branch of Tyrann's quake 1 tools, focused on adding
lighting features, mostly borrowed from q3map2. There are a few bugfixes
for qbsp as well. Original readme follows:

A collection of command line utilities for building Quake levels
and working with various Quake file formats. I need to work on the
documentation a bit more, but below are some brief descriptions of
the tools.

Included utilities:

  qbsp    - Used for turning a .map file into a playable .bsp file.

  light   - Used for lighting a level after the bsp stage.
            This util was previously known as TyrLite

  vis     - Creates the potentially visible set (PVS) for a bsp.

  bspinfo - Print stats about the data contained in a bsp file.

  bsputil - Simple tool for manipulation of bsp file data.