Add plumbing for the SceneObjectDeleter to wait for the script engine to

allow final deletion of objects. Meant to support the attach(NULL_KEY) event,

OpenSim/Region/Framework/Scenes/SceneObjectPart.cs

@@ -3787,5 +3787,10 @@ if (m_shape != null) {
 
             Inventory.ApplyNextOwnerPermissions();
         }        
+
+        public bool CanBeDeleted()
+        {
+            return Inventory.CanBeDeleted();
+        }
     }        
 }