Clarify the tests in embedded_test.go to indicate that unmarshalling
of an internal object (runtime.EmbeddedObject) will not work. Instead,
consumers should decode raw external objects.
* Make Codec separate from Scheme
* Move EncodeOrDie off Scheme to take a Codec
* Make Copy work without a Codec
* Create a "latest" package that imports all versions and
sets global defaults for "most recent encoding"
* v1beta1 is the current "latest", v1beta2 exists
* Kill DefaultCodec, replace it with "latest.Codec"
* This updates the client and etcd to store the latest known version
* EmbeddedObject is per schema and per package now
* Move runtime.DefaultScheme to api.Scheme
* Split out WatchEvent since it's not an API object today, treat it
like a special object in api
* Kill DefaultResourceVersioner, instead place it on "latest" (as the
package that understands all packages)
* Move objDiff to runtime.ObjectDiff
This is some cleanup that has been needed for a while.
There's still one more step that could usefully be done, which is to
split up our api package into the part that provides the helper
functions and the part that provides the internal types. That can come
later.
The v1beta1 package is now a good example of what an api plugin should
do to version its types.
