add orginal event to callback param

[anhnhoktvn]

No description provided.

[dy]

There are also touchpinch and wheel places, where the pan-zoom event is formed up.

[anhnhoktvn]

The touchpinch library did not expose the touch event, could you give any suggestion?
The wheel is already added.

[dy]

I was trying to add original event too, but hit the same wall. Considering that impetus and touch-pinch are unlikely to change API to expose the event, I'd suggest bringing required parts of their code here, in this repo. That would allow significantly reduce size and deps. Esp. impetus - that's a bit of overhead.
touch-pinch is experimental anyways and creates a bunch of related unfixable bugs.