Actually make EventManager.OnAttach() fire when an object is attached. Previously, only detach was firing!

OpenSim/Region/Framework/Scenes/SceneGraph.cs

@@ -540,6 +540,9 @@ namespace OpenSim.Region.Framework.Scenes
                     // Fire after attach, so we don't get messy perms dialogs
                     // 3 == AttachedRez
                     objatt.CreateScriptInstances(0, true, m_parentScene.DefaultScriptEngine, 3);
+
+                    // Do this last so that event listeners have access to all the effects of the attachment
+                    m_parentScene.EventManager.TriggerOnAttach(objatt.LocalId, itemID, remoteClient.AgentId);
                 }
                 return objatt;
             }