emit on-change event when selection in options changes
Added ability to make multiple lines of tabs in TabStack
updated haxelib for development, adding src as classPath
add ability to reverse transition
reverse transition when hiding popup in Options widget
reverse transition when going back in ViewStack
added forgoten ","
Allow skins to unDraw/reDraw them, when chaging skins.
* The first time a skin is applied to a widget "draw" is called
* When a skin is re-applied, "reDraw" is called (by default it calls unDraw and draw)
* When another skin is applied, "unDraw" of the last skin is called.

For this "_appliedSkin" has been moved from "Button" to "Widget".
Updated layer skin to correctly draw and undrawing of the child skins
added Filter skin class
registered classes for filter skin
Added missing super constructor call/corrected typo