Implement RPC for JDO persistent objects.
The JDO object must contain the annotation:

@PersistenceCapable(identityType = IdentityType.APPLICATION, detatchable = "true")

and be detached at the time it is sent to the client as part of an RPC request.

For now, the WeakMapping API is in an impl/ package and excluded from API checking.

Review by: bobv



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5672 8db76d5a-ed1c-0410-87a9-c151d255dfc7