MESSY now works for NPC's and player hits.

Fixes: https://github.com/CleverRaven/Cataclysm-DDA/issues/6727

Reworked the creature code. bloodType and gibType are now virtual, and character and monster have overloaded versions.
Mtype also has a bloodType and gibType.

I had some issues getting it all to compile due to circular includes. Hope it all works now.