Pin Fix

Pins wouldn't unpin when reverse is false and scrolling back up during
scene.
Fixed with a workaround to unpin at start.
Unpinning at same position will require a lot more thought and might
even be undesired… check TODO.
changed option "smoothTweening" to "tweenProgress"

also some other minor tweening3 changes
Cleanup

- removed finished todos
- some comment changes
- added destroy method
- changed .unbind to .off for consitency reasons
- added test html and example for scroll container use