Lightbox as an object

Man this makes so much more sense.

New interface (methods of the new global Lightbox object):
- get(controller, action, get, post, callback)
- getByUrl(url, post, callback)
- addCloseAction(function) - function to run after lightbox closes
- addOpenAction(function) - function to run when the lightbox loads
- addFormHandler(name, function) - full handling of submission, must call ajax, must return false
- addFormCallback(name, function) - function to run the response from the automatic form ajax submission
- changeContent(html)
- close()
- confirm(message) - replace content with formatted message and close button