• Made the Ammo Box into a Medium Item. Should keep it from fitting into other containers meant for small items.
  
• Made an explitic exception for containing Ammo Boxes inside Ammo Boxes. Don't think it does anything, but it doesn't hurt, either.
  
• Refactored the allowed items. Removed all the grenade special-case exceptions and went with the generic "explosives." As a result, the Ammo Box now also holds plastic explosive items.

Fixed the Ammo Box's "body." It should interact with walls, floors and other physics objects correctly now, and should also be about twice as heavy. It was using a copy of the much smaller Toolbox's physics body.

Initial release.