Scroll timeline horizontally with horizontal mouse scroll wheel

[from the forum:](http://esotericsoftware.com/forum/Kind-request-Scroll-sideways-in-the-timeline-11540)
> I would like to kindly request a horizontal scroll, in order to improve the timeline navigation through the keyframes.

>Now I use RMB+Drag to Pan through the timeline, and it would be awesome to have the option to scroll sideways, also by using the horizontal scroll of the mouse, for the users that have this option on their mouse. ( I use this in After Effects and I find it very useful.)