Maya Selection Work

API - Added a BaseDict class that extends Base Struct
API - BaseStruct's now have the ability to be serialized and
deserialized.  Assuming the derived class is set up properly this
should work flawlessly
API - Updated Document to use BaseDict
Maya - Selection and ObjSelData use BaseDict
Maya - Selection class almost fully blocked out, just need to wrap up a
few more loose ends with handling the selection and pulling data from
it.  Also need to implement the lazy loading of other data related to
the selection