initial implementation of alert component
Merge branch 'master' into alert
Alert: better layout choice
docs fix
Scroller: mouse wheel only works inside content bounds (so that panel doesn't scroll when mouse wheel turns over header and footer) (closes #645)
LayoutGroup: clipContent works when width or height is zero (closes #644)
Scroller: clipRect width and height must be at least zero
TabBar: cleaned up selection handling (closes #635)
PopUpManager: centered pop-ups stay centered wwhen the stage resizes (closes #638)
Callout: backgroundSkin is not required (closes #626)
Text editors: better handling of scaling
StageText: better scaling
StageText: support for rotation
removed trace
TextFieldTextEditor: support for rotation (font must be embedded)
Button: improved touch phase handling for recent Starling change
Virtual layouts: better typical item handling
Scroller: won't scroll with mouse wheel when scroll policy is off
Further work on typicalItem replacing typicalItemWidth and typicalItemHeight. Added resetTypicalItemDimensionsOnMeasure to go back to better 1.0.x behavior while still allowing 1.1.x behavior of resetting typical item dimensions. fixed some issues with caching in vertical and horizontal layouts
List, GroupedList: stability fixes for typicalItem used by layout. GroupedList: removed typicalHeader and typicalFooter, since they aren't used anymore.