Sound effects for mobs dying and taking damage

[MirceaKitsune]

Allows defining a sound for mobs dying, and a sound for mobs taking damage. Code implementation only, no changes to the default mobs. Tested in my Creatures mod where the same code is used for those sound effects.

[hildigerr]

I have included this merge downstream, and then expanded on it to allow different sounds for various ways of dying and taking damage.