Correct a mistake in the COPersistentRoot -rootObject docs: references in other persistent roots to rootObject are just a pointer to rootObject, there is no observing of change notifications or resolving which branch is the current branch at deserialization time. Also mark -allObjectGraphContexts as private

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10496 7b3f36aa-e6db-49c1-8b4c-66eac1997e64