public interface IRegistryDelegate<T>
A registry delegate for holding references to items or blocks
These should be safe to use in things like lists though aliased items and blocks will not
have object identity with respect to their delegate.
Get the referent pointed at by this delegate. This will be the currently active item or block, and will change
as world saves come and go. Note that item.delegate.get() may NOT be the same object as item, due to item and