In bringing back Clayton's PR piece-by-piece this was almost as easy to
implement as his version, and is much more like what I think we should be
doing.
Specifically, any time which defines a .DeepCopy() method will have that method
called preferentially. Otherwise we generate our own functions for
deep-copying. This affected exactly one type - resource.Quantity. In applying
this heuristic, several places in the generated code were simplified.
To achieve this I had to convert types.Type.Methods from a slice to a map,
which seems correct anyway (to do by-name lookups).
Make unversioned.ListMeta implement List. Update all the *List types so they implement GetListMeta.
This helps avoid using reflection to get list information.
Remove all unnecessary boilerplate, move the interfaces to the right
places, and add a test that verifies that objects implement one, the
other, but never both.
Remove Codec from versionInterfaces in meta (RESTMapper is now agnostic
to codec and serialization). Register api/latest.Codecs as the codec
factory and use latest.Codecs.LegacyCodec(version) as an equvialent to
the previous codec.
