Make EventManager adds a class touchEnabled
to the canvas element when it detects a touch
event (because simply sniffing for the existence
of touch events is not reliable).
Only show the selection handles of the
shadow cursor and the local cursor.
Just in case, to prevent any leaks due to interrupted
gestures, clear all longpress timers on EventManager.destroy()
Avoid timer leaks: store and delete timers
in and from an object in the emitLongPressEvent
proxy.
Inject srcElement property in CompoundEvents
for IE