Fix clone to account for the update list added for update

optimization.  The updateList was cloned also and needs to
be cleared out and the update flag reset as if freshly
initialized.  Thanks for lightbringer for pointing out the
problem and solution.

jme3-core/src/main/java/com/jme3/scene/Node.java

@@ -687,6 +687,11 @@ public class Node extends Spatial {
 //            childClone.parent = nodeClone;
 //            nodeClone.children.add(childClone);
 //        }
+
+        // Reset the fields of the clone that should be in a 'new' state.
+        nodeClone.updateList = null;
+        nodeClone.updateListValid = false; // safe because parent is nulled out in super.clone()
+            
         return nodeClone;
     }