Void Dwellers

First PR. Void Dwellers are a new mob, intended to spawn rarely in deep
space. I don't know how to do this, but the basic mob is now coded. They
have 40 health, do 10 brute damage per hit, and can move freely in
space. They leave no corpse or loot. I leave the actual spawning to
someone with the knowledge to do so properly.
Merge pull request #413 from Thunder12345/master

Void Dwellers