Support for zoom in/out

[alexwhittemore]

I'm not even sure if this is a valid HID thing or if i.e. wireless touchpads do it some other way, but I'd love zooming support like pinch-to-zoom, but via some non-multitouch input. If anyone coming across this issue has any idea how to implement that, or an example like an open source mouse firmware or something, please do let me know.