[New Feature] Allow for horizontal scrolling via touchpad with mouse-wheel-plugin

[peterschmidler]

What problem does this feature solve?

Horizontally scrollable pages cannot be scrolled via my mbp's touchpad, since the mouse-wheel-plugin only captures vertical and no vertical wheel events.

What does the proposed API look like?

A horizontal:bool paramater could decide weather horizontal deltaX values should be considered.

[peterschmidler]

Horizontal scrolling is indeed possible, but only via up/down scrolling and not via left/right scrolling on touchpads.

[peterschmidler]

I think there's no parameter needed and the issue could easily be solves as in my pull request.

[theniceangel]

fixed at v2.4.2