COUndoTrack: tweak menu item title convenience methods

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10236 7b3f36aa-e6db-49c1-8b4c-66eac1997e64
Added test assertions in -testPersistentRootAccessors that validate the behavior 
documented in -persistentRootForUUID:


git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10237 7b3f36aa-e6db-49c1-8b4c-66eac1997e64