Slider drag events

[Zingabopp]

Exposes DragStarted and DragReleased events for GenericSliderSetting. Added BSML Properties to GenericSliderSetting:

• updateDuringDrag: If true, changes to the value will raise events while being dragged (default, previous behavior). If false, events for value change will only be raised after the slider is released.
• onDragStarted and onDragStartedEvent raised/emitted when the slider is grabbed.
• onDragReleased and dragReleasedEvent raised/emitted when slider is released.

I wanted to do a TypeHandler for DragHelper itself so it could be easily attached to any component, but it needs to be attached to the same GameObject as the base game component so BSML doesn't pick it up. I left the DragHelperHandler in there (commented out) if you can find a way around it.