[WIP] Adds skulls and bones
Created by: unid15
- Added /obj/item/stack/animal, and made teeth a subtype of that
- Added a "has_skeleton" var to living mobs
- Added bones. They drop from animals after butchering, and can be used to build bone furniture (WIP: NEED SPRITES!)
- Added skulls. They drop from animals after butchering, using a chisel on one makes a helmet (WIP: NEED BETTER SPRITES)
- Remains can be collected by clicking on them with an empty hand, yielding around 20 bones and a skull