Display traits cleanup

- Move `var visible` back into IPositionable.
- Remove scaleX from IGraphicsOwner.
- Make `var filters` compatible with NME.
- Remove dead scaleX,Y properties from UIWindow.
Rename 'float' to 'floating' for C++ compatibility
Fix multiple C++ compile errors

- Bindable needs generic because of being extended
  by the RevertableBindable generic class.

- Comment unused SliderBase.inverted setting
- InputFieldSkin fixes
- Simplify inline-ability of TextField.removeFocus
Fix NME HTML5 debug build startup exceptions.
LayoutExample4 as NME app (in examples/nme_test)