Add missing EV_USE_ITEM15 cases

Add EV_USE_ITEM15 to cg_event.c and ai_dmq3.c for consistency.
Fix pid file ignoring user set fs_homepath

Create pid file in fs_homepath instead of (always) default homepath.
If not manually set, fs_homepath is set to Sys_DefaultHomePath().
Always use GL_Cull to change cull state

Manually changing cull state can cause later GL_Cull calls to not change
the cull state.
Merge remote-tracking branch 'ioquake3/master'

Conflicts:
	code/cgame/cg_event.c
	code/game/ai_dmq3.c
	code/sys/sys_main.c