cubiq/iscroll — pull request #585 by SansWord (2014-01-13 09:21:05+00:00)
Title: Change off's behavior: If fn is not given, all event handlers of given t...

Sometimes when we using on to register a callback, the function usually have no name.
So I need a method to unregister all callbacks of given type.

In jQuery, when no function is given, all handlers of given type will be unregistered, which I consider useful.
So I implement it in iScroll, hopefully can be accepted.