GRAW2: SP Kit adjustments

[Wolfsong]

While I'm at it fixing around the MP kits, I figured I could fix up the SP system some so the team member in SP have a bit more variation.

Limited "sniper" class to only use sniper weapons.
Limited "support" class to only use support weapons.
Added support for limiting weapon mods to classes.
Limited combat sights and front grips to "rifleman" class.
Limited grenade launchers to "demolitions" class.
Added G36K and G36C to SP kits.
Fixed inventory selection icons for G36K and G36C.

I will include these changes in a mod together with the other weapon changes and draw distance changes.

The player in SP is of course "team leader" class, so he has access to all weapons and weapon mods as usual.