Update LibUtilExt/Command.

- CommandHistory into separate module.
- Replace Listener by onUndoRedoChanged MultiProcedure.
- Add PADrend.CommandHandling.executeRemoteCommand
- Adapt to changes.
Improve effects.

DynamicSky:
 - Code cleanup
 - Don't write into the depth buffer
InfiniteGround:
 - Code cleanup
 - Improve position update (use state instead of extensionPoint)
SSAO2:
 - Add haze.
Add PADrend.SceneManagement.assureScene(...).
LibGUIExt: Add visual hint if components have a context menu.
UniversalShader3: Improve surfelSize-shader.
ObjectTraits/Animation/ButtonTrait: Sync button action.