Fix missing materials on the half life 2 and counter strike shotgun shells

fix a few small lua errors, revamp the 2 handing system (ported over from the beta branch) and finally fix the grenade - hopefully maintain this addon for the future

bunch of new stuff, preparation for wave 2 launch

introduced hitscan and new shotgun grip mechanics, updated description to account for those
adjusted grip positions on the pistols since users reported they were being held too high (and generally the handposes look less ugly now)
also added a new gun: the silenced USP from CSS

Should have fixed the HL2 VR weapon giver not working

Hopefully fixed an error with shotgun shells when using shotguns in preparation for wave 2 remake.