mint-arena: Fix vid_restart while in-game not setting up viewport

Causes text not to render at info screen and crash when opening console.
mint-arena: Make sure console field isn't bigger than buffer
Fix an invalid null deref check in the slider code.
mint-arena: Allow disabling skybox ground surfaces

RTCW SP allows disabling the non-sky surfaces. In RTCW SP, disabling
the sky box actually only disables the ground in the skybox.

Put this behavior at cg_skybox 2 instead.
mint-arena: (re)move defines at top of q_shared.h

Move three non-engine defines at the top of q_shared.h to bg_public.h.
Remove the engine defines.
mint-arena: Move fontInfo_t to tr_types.h
mint-arena: Add %x to bg_lib.c's sscanf from Tremulous
mint-arena: Add warning for unsupported format chars in sscanf
Merge remote-tracking branch 'mint-arena/master'

Conflicts:
	code/game/bg_public.h
	code/qcommon/q_shared.h