Removed signalUnreffed interface

include/osg/Observer

@@ -27,13 +27,6 @@ class OSG_EXPORT Observer
         Observer();
         virtual ~Observer();
 
-        /** objectUnreferenced(void*) is called when the observed object's referenced count goes to zero, indicating that
-        * the object will be deleted unless a new reference is made to it.  If you wish to prevent deletion of the object
-        * then it's reference count should be incremented such as via taking a ref_ptr<> to it, if no refernce is taken
-        * by any of the observers of the object then the object will be deleted, and objectDeleted will in turn be called.
-        * return true if the Observer wishes to removed from the oberseved objects observer set.*/
-        virtual bool objectUnreferenced(void*) { return false; }
-
         /** objectDeleted is called when the observed object is about to be deleted.  The observer will be automatically
         * removed from the observerd objects observer set so there is no need for the objectDeleted implementation
         * to call removeObserver() on the observed object. */
@@ -54,8 +47,6 @@ class OSG_EXPORT ObserverSet
         void addObserver(Observer* observer);
         void removeObserver(Observer* observer);
 
-        void signalObjectUnreferenced(void* ptr);
-
         void signalObjectDeleted(void* ptr);
 
         typedef std::set<Observer*> Observers;