logic to remove jsb.on-registrations as soon as the dom element disappears

[DracoBlue]

In some projects we have the problem, that lots of ajax code is replaced by new ajax code. In this case some jsb-handlers are registered on dom elements, which are already removed from the dom and will never be inserted again.

Usually this is not a problem at all, since you won't run into memory nor cpu issues if you don't register thousands of events within seconds.

But: It would be cool to fix that issue. ;)

Ideas are:

• add an "unbind" event, which allows the instance to cleanup (e.g. call unbind or jsb.off)
• to replace the listener logic with something like https://developer.mozilla.org/en/docs/DOM/element.addEventListener and let the browser take care of the garbage collection
• ... ideas?

[DracoBlue]

Fixed with 3ba7a975dd1e1b3ad8533343c503a68f12b50c13