Add demo/js/underscore-min.js
Make the events demo IE8-friendly
Add workaround for IE8's unusual dblclick sequence

http://www.quirksmode.org/dom/events/click.htm
>Events leading to dblclick

A tap is fired when a dblclick happens. The tap the fires a doubletap.
Fix hold events in IE8
Only remove from pointers array if not interacting