mint-arena: Update cg_public.h

The value is used internally by the engine for range checking.
mint-arena: Remove bg_public.h (contaning PERS_SCORE) for server

File is not used by the game code.
mint-arena: Return bg_misc.h to it's rightful name, bg_public.h
mint-arena: Only need one cg vmCvar for ui_singlePlayerActive

Don't make cg_singlePlayer MISSIONPACK only. Q3 code uses, not used in cgame yet
but it's annoying to have to move it outside MISSIONPACK in other games.

Leave ui_singlePlayerActive vmCvar_t in missionpack UI, for now at least.
mint-arena: Make bots stop attacking player after disconnect

Bots did not notice player disconnected, so they kept attacking
the last known position.

Checking in BotEntityVisible might fix other similar issues too.
mint-arena: Don't use uninitialized ps from BotAI_GetPlayerState

If BotAI_GetPlayerState returns qfalse, ps is untouched and in
some cases means uninitialized. So don't use it if not valid.
Merge remote-tracking branch 'mint-arena/master'