Overwrite method if request for _method is present

I really like this simple router, I think it would be a touch more flexible if you were able to overwrite the request method with a simple hidden input (a similar implementation to RoR). This would mean that users don't have to use XMLHTTPRequests to do PUT or DELETE requests. It's only an extra IF check, so hopefully doesn't 'bloat' the software too much IMO, but what do I know!