fix issue #76 Deleting a clone of an object with a custom class breaks the original object.

engine/source/sim/simObject.cc

@@ -1128,7 +1128,7 @@ void SimObject::copyTo(SimObject* object)
 {
    object->mClassName = mClassName;
    object->mSuperClassName = mSuperClassName;
-
+   object->mNameSpace = NULL;
    object->linkNamespaces();
 }