SimpleXMLElements

One of the things that was stopping Magento from running on Quercus and other non-offical PHP runtimes was the fact that it used custom SimpleXMLElement sub-classes. A not often used feature of the simplexml library. While it's quite handy to add your own behaviors onto each element, it's not necesarry either. I've moved all the element methods on to the base config classes, thus reducing overall memory and hopefully allowing agent-ohm to run in places that Magento won't.