- merge net_udp6.c into net_udp.c
- kill off ctf/q_shared.c, it's identical to src/q_shared.c
- clean up the #ifdefs that are throughout the code to be has-a
  tests instead of is-a. (using HAVE_* from configure instead of __blerg__)
- separate the video refreshers
- use DATADIR to find game data, rather than in same directory as libraries
  this way, it can follow FHS: libs in /usr/lib/games/quake2 and data in 
  /usr/share/games/quake2, for example