Weapon FANCY kits

Based on a random idea I got while reading the forums.

Adds a handful of cosmetic weapon kits for weapons, such as gold
plating, silver plating, chrome plating, and a "bling" kit consisting of
diamond studded gold plating.

Works perfectly on weapons with shoulder straps, but I haven't figured
out how to make it work on holstered or wielded weapons.
I wouldn't expect launchers to have pistol-grips, probably not most of our current shotguns either.  Suggest genericizing the grips.