Events should be namespaced

[mattflaschen]

There is a call to unbind that unbinds all keydown handlers on document, not just those added by guiders.

The easiest solution for this is to use jQuery's namespaced events. Strictly, it is only needed when you're doing an unbind. But for consistency (and so unbinds can be added easily later), it's better to do it everywhere.

I will try to do a pull request for this shortly.