skidding/dragdealer — pull request #66 by herrernst (2014-12-12 11:11:02+00:00)
Title: Startdrag stopdrag callbacks

Hi,
for my use case of dragdealer I need explicit drag start and drag stop callbacks (there's already a target callback, but it is also triggered when the target value is set programmatically via ```setValue()```).
I would be quite happy if you could add them.
By the way, thank you for your work!