Prevent vertical scrolling when sliding horizontally and using autoScrolling:false

It was reported that:

> The natural gesture of the thumb swiping left or right on a phone has a somewhat downward trajectory which triggers a downward scroll. I don't know if there is a way to fix that so it only scrolls left or right, but it definitely impacts the user experience on mobile. I would prefer to use autoscroll:false on mobile but with that scrolling issue it is too frustrating for users. Just thought I would point that out in case in some future update it could be addressed. I didn't want to make an issue on github because it's not really a bug but if you prefer I make an issue about it I can.

Reproduction online on [the example page](http://alvarotrigo.com/fullPage/examples/normalScroll.html).