Make UIs work with case sensitive file systems

pk3s aren't case sensitive, causes issues running on Linux with upzipped files.
Merge remote-tracking branch 'spearmint/master'

Conflicts:
	code/q3_ui/ui_loadconfig.c
	code/q3_ui/ui_servers2.c
	code/q3_ui/ui_startserver.c
	code/ui/ui_main.c
Remove leftover SUPPORT_LINUX_NO_PAK stuff