Add support for scroll wheel buttons to perform three finger swipe desktop switch

[girivs82]

In addition to the side buttons, it would be awesome if we could also have support for three-finger desktop switch swipe simulated for the scroll wheel buttons on mice that have scroll wheel buttons. I realise this expands the scope of the app beyond the side buttons, but the hard work is done anyway and the swipe simulator can simulate three finger swipe (IIRC).

[dn0sar]

Not exactly what you wanted, but I added support for spaces switching with #82 if you want to try it