Click Trampolines - support to trampoline pointer events into 'click' events

- This is needed to support Fullscreen on IE11 because IE only trusts 'click' events for this operation; click trampolines as a general solution, although they are only required in some "special" cases.

This implementation is designed around the idea that click-trampolines are rare; the 'click' handler installed is for trampolining, but could be adapted to be registered/deregistered when click trampolines were added.

This works to fix https://github.com/photonstorm/phaser/issues/1281