Interpolate snapping/resticting with the endOnly option when inertia isn't triggered

[taye]

If inertia is enabled on an Interactable, snap/restrict has the endOnly set to true and snap/restict occurs when the pointer is release without triggering inertia, then the event coordinates will be animated from the release location to the snapped/restricted location.

interact('*')
  .inertia()
  .snap({mode: ..., endOnly: true})
  .restrict({drag: {...}, endOnly: true});

The duration of the animation can be set with

interact('*').inertia({
  smoothEndDuration: 300 //  the duration in ms
})

Closes #48

[taye]

@jordandh I've implemented this a little differently to how I imagined before. Rather than having a smoothEnd option in snap and restrict, it just happens automatically if inertia is enabled and snap or restrict endOnly is true.

If you have time to test it I'd greatly appreciate it!

[jordandh]

@taye I will take a look at this this week. Hopefully tomorrow or Wednesday.

[jordandh]

@taye I tried out the snap-restrict-smooth-end branch and it works well for the most part. I was even able to remove my draginertiastart handler code because your changes do the job for it.

The only problem I noticed happens when you begin a drag during another drag's inertia phase. The interactable snaps to the incorrect coordinates. This may be due to the way I use the snap functionality. First I set the snap on the interactable like so:

.snap({
  mode: 'anchor',
  endOnly: true
})

And in my dragstart handler I set the anchorPoints as described here #32 (comment)

I'll post again if I obtain more information.

[taye]

I think that the fix for the inertia zeroResumeDelta issue is ready now and that should fix the problem you described above. I'll start merging things and hoping that they aren't too broken :).