Motion behaviour: Timed two-way motion

[GrandyB]

Another one for the new motion behaviour drop-down. Once we have the core functionality clear and stable, we should probably try make it a little more automated. This behaviour type would be particularly useful for having like sponsor logos come onscreen for a short while before disappearing, same with caster names or general notifications.

• Predefined point A and B
• Single hotkey to begin the animation
• New int property for "hold duration" (N seconds)
• Automatically performs "backward" action N seconds after finishing the forward animation

Considerations:

• Maybe keep both hotkeys and cancel the hold if the backwards hotkey is pressed?

[JackLyttle]

I'd be keen to have an animation run from A to B and back again indefinitely.