Embedded projectiles/pneumatic cannon.

- Items will now embed in a human if they do sufficient damage and are sharp or roll well on the prob() check.
- Large embedded items will show up on examine, but tiny items will not.
- Solid projectiles will now possibly leave shrapnel in the wound.
- Embedded items/shrapnel show up as unknown bodies in the body scanner and can be removed via implant removal surgery, with no additional harm, or by hand if their w_class is 2 or more, which has a 10% of causing internal bleeding and a 100% chance of being gnarly and messy.
- Moving with shit embedded in your body will cause bleeding, toxin and brute damage periodically.