Some types that have registries support existing without
being in a registry and therefore have no key. This is part
one of supporting that, adding a Registry#getKey(Object) method
to be able to get the key for an object so we can remove Keyed
from such objects.
This also deprecates Keyed#getKey on TrimMaterial and TrimPattern
as these are the 2 offending types currently in the api.
