Revamping the reference system

Now an RL_Ref can be used to refer to an arbitrary location in space, or
a specific object, or to a location relative to an object, wherever that
parent object is. It could theoretically be used for more complex ways
of referring to things in the code in the future but this is all we need
for now.

RL_Ref's should NEVER be accessed directly with . or ->; use the getters
and setters.