Specify fs_homebase for q3map2 invocation

This allows q3map2 to use ~/.padman/ on Unix. Unfortunately
q3map2 does not have an equivalent for Windows.
Use game "quake3" for q3map2 invocation

q3map2 does not have a game_wop.h or similar, so it defaults to
"quake3" anyways, since "wop" is not recognized.
WoP still needs -custinfoparms.