Fix a possible buffer overflow: mbstowcs takes character, not byte, count.
Some windows fixes
Don't execute default.cfg on dedicated server

Default.cfg only contains binds and the server doesn't care about that.
This also stops the Command not found spam when starting a server.
Fix crash upon openning menu when not using OpenAL

Thanks Fuma for debugging
Quick fix for the options menu not working for latched cvars
Cvar: handle the case where a NULL string is sent to Cvar_Set
Only set ROM startup variables once
More mbstowcs overflow fixes. Again, byte count v. element count.

Conflicts:
	src/engine/client/libmumblelink.c
Fix diffuse/normal/spec maps used with r_picmip

We were erroneously setting the forcehighquality flag instead of the nocompression flag