ability to simulate touches with keyboard

[dmalan]

Helpful for testing.

[LincePotiguara]

I noticed that metaKey is used to simulate diferent touches events.
On Windows this key opens the Start menu which is too annoying.

I suggest to map to other key like Ctrl or Alt by adding a second check in the mc.on() function.
ev.srcEvent.altKey or ev.srcEvent.ctrlKey should work.