Feature: SlidingUpPanel with drag support

[niconaso]

First of all I would like to congratulate you for this excellent job!
I would be great to have a handle to drag up and down (or left and right) to open and close the panel like in this example: https://www.joshmorony.com/how-to-create-a-sliding-drawer-component-for-ionic-2/

Thanks!

[arkon]

This is sort of related to #1, which I wanted to do but it's pretty complicated with how complex the component's become. 😅