Ignoring vertical swipes

In response to the (already closed) issue https://github.com/freerunnering/SwipeSelection/issues/4, I have implemented ignoring vertical swipes for users of international keyboards on iPad where swiping vertically provides quick access to special characters.

I have also increased the deadZone in order to avoid inadvertent scrolling on subsequent nearby keystrokes.

Tested on iPad 3, works as expected without issues.