mint-arena: Don't hard code weapon names for bot chat
mint-arena: Register bot_testichat cvar

Makes it show in cvarlist and able to auto-complete it.
mint-arena: Support ctflocation if teamlocation does not exist

Q3 pak4.pk3 renamed "ctflocation" in botfiles/teamplay.h to "teamlocation".
(because of new Team Arena gamemodes.)

Q3 demo and Elite Force still use ctflocation, so fallback to 'ctflocation'
if there are no 'teamlocation' chats.

However, pak4.pk3 broke match.c compatibility so need to remove EC from
chat message in Game VM for bot to notice you're talking to it. Ideally
I'll remove the need to do this later.