Feature/scrollevent callback

[ejkkan]

Callback so that you can recieve the scroll event for custom implementations. For example a custom animated header depending on the scroll values

[i6mi6]

Thanks, @ejkkan

[wowtrxqn]

A drag and drop container is nested inside the ParallaxScrollView.
How to ensure that the sliding of ParallaxScrollView is not triggered when dragging internal components？

Thanks, @ejkkan