Scroll via translation rather than updating every widget's bounds

[hrj]

When scrolling, RCollection.updatWidgetBounds() is called recursively on the sub-scene. Not sure what the reasons are, but we could potentially optimise this through a translation of the graphics context of the node that is being scrolled.

[hrj]

The updateWidgetBounds() only updates the native Swing components (such as input fields, scroll bars, etc). So this is not as bad as I first thought.

Can still be investigated further though. First thing to do would be to benchmark and to decide if it is worth optimising.