Minor Issue: Incorrect cell change if mass cell movement

[Chris-Perkins]

Noticed this in the latest build. iOS 10.3.1

If you click and drag one view, then rapidly move it up and down between some views, one view will stop moving and stay either higher or lower than it should. After dropping the selected cell when this occurs, the cell which was misplaced earlier will sometimes teleport to another location.

Thank you for the great library. Saved me a lot of stress, and the code is very top quality. :)

EDIT: Noted that an issue was closed for it here, although the bug does still seem to persist: #5