Touch events support

[gssvv]

Fixes a bug when using the plugin with touch events (line touchstart) does not make any sense.
The problem was that touch events do not have event.clientX and event.clientY. Instead, have event.touches that keeps an array of touches. I use first of them to get clientX and clientY for ripple style.
So if event.clientX is unavailable, we refer to event.touches[0].clientX. The same is for clientY