COObject: implement +automaticallyNotifiesObserversForKey:. The KVO programming guide requires us to do this because COObject sends manual KVO notifications (it calls -willChangeValueForKey:, -didChangeValueForKey:, etc.). In TestObjectUpdate, validate the number of KVO notifications received (exactly 1). Prior to this change, you would get redundant KVO notifications if you observed a property on a COObject subclass, because the KVO system would not know that COObject manually sends KVO notifications, so it would do the dynamic subclassing trick.

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10042 7b3f36aa-e6db-49c1-8b4c-66eac1997e64