TestBranch: Expand the garbage related tests. Add a test (disabled for now) for a problem I noticed while testing typewriter; we load all items returned from the store, even those that are unreachable (which means there is no point loading them as COObjects).

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10288 7b3f36aa-e6db-49c1-8b4c-66eac1997e64