Assign to `cancelFrame` variable
autoScroll takes speed option and uses reqFrame

interact.autoScroll({
    margin: 50,
    container: element || window,
    speed: 300 // pixels per second
});
Add "endOnly" snapp setting

`interact.snap({endOnly: true})` will not snap coordinates while the
pointer is moved by the user. When the pointer is released, a move
event is created, snapped and fired immediately before the end event.
Set snapStatus and restrictStatus in functions
Add "status" parameter to setSnapping

Snap status properties are assigned to this object if it is provided
Replace repeated path snap code with anchor snap

Also fixes unexpected behaviour of the possibility of snapping to x and
y of different paths
Make "endOnly" restriction option functional
Use native requestAnimationFrame if available
Merge branch 'master' into inertia

Conflicts:
    interact.js
Improve inertia decay and fire inertiastart events
Implement quadratic bezier inertia end snapping
Prepare for smooth inertia endOnly restrictions
Merge branch 'master' into inertia
Implement smooth restrict endOnly during inertia
demo/snap: add a basic demonstration of inertia