Species and organ fixes.

Fixes issues with post-spawn alien species not rebuilding the HUD properly.
Fixes issues with decapitation (or gibbing) involving a mob with missing organs.
Fixes issues with reviving a mob with missing organs.
Fixes a runtime error with mobs with no brains calling getBrainLoss().
Refactors organ transplant code to be easier to maintain. 
Refactors and generalizes severed organ internal organ removal surgery (scalpel, retractor, hemostat).
Neatens up some issues with explosive gibbing, organs, and the gibber from my previous PR. Organs will get flung around properly now.
Removes redundant weapon/organ/head brainmob/personality transfer code (just uses the brain organ item now).

- [X] Check species HUD updates.
- [X] Test brain death message.
- [X] Test gibbing.
- [X] Retest gibbing/organ throw fixes, dionaea.
- [X] Test beheading.
- [X] Test dismemberment.
- [X] Test severed organ removal.
- [X] Test head reattachment.
- [X] Test beheaded revive.
- [X] Test organ removal surgery.
- [X] Test organ replacement surgery.