Small tweaks to Camera, Game, and Component.
Initial commit of XMLDict object.

A helper class for read-only manipulation of an xml document. Mostly
lifted from Cory Fabre's excellent recipe at:
http://code.activestate.com/recipes/573463-converting-xml-to-dictionary-and-back/
Initial commit of plugin module and ogmo module.

Implemented the ogmo module to create Scenes from Ogmo levels.