reworked transparency in palettes, made palette_complete be strictly opaque, added...

reworked transparency in palettes, made palette_complete be strictly opaque, added palette_transparent (and switched a few things over to it), made palette_font actually be used (and it no longer has a transparent color 255, only color 0 is transparent in the font, correctly matching software quake), this should hopefully fix bugs with models using color 255 in their skin

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5865 d7cf8633-e32d-0410-b094-e92efae38249