Andreas Mokros's macro CFFI solutions and components, Mister Pah's ListBox addition

Added Andreas's macro-driven solution for generating properties and eventhandlers on the fly from the cpp origins. Implemented in ControlWithItems, ListBox, RadioBox, ScrollWindow. With slight modification this now works in Haxe 3.1.3. 
Added Mister Pah's ListBox.set(items) method.
Added new demo, samples/06-Controls.
Minor cleanups.