Copying user objects was missing."
Note from Robert Osfield, in submission changed
_objectList.push_back((*itr)->clone(copyop));
to
_objectList.push_back(copyop(*itr));
with a osg::DefaultUserDataContainer subclassed from this. The user object access methods have now all
been moved from osg::Object into the UserDataContainer class, except for the set/getUserData() methods
that are left in osg::Object for backwards compatibility, and the description list access methods have
been moved back into osg::Node.
main UserObject access methods are now all def
