[BUG #8560] Minor update of the play app
[BUG #8560] Replaced id property with getAttribute
[BUG #8560] Moves statics to the top of the file and removed the widget registry (not necessary anymore)
[BUG #8560] Removed the old picker implementation
[BUG #8560] Updated widget auto id test
[BUG #8560] Override setAttribute instead of offering _setAttribute parallel
[BUG #8560] Removed duplicated method
[BUG #8560] Removed unused internal function
[BUG #8560] Removed deprecated methods
[BUG #8560] Removed isVisible, isHidden, isExcluded and isSeeable
[BUG #8560] Use readonly instead of readOnly (like the DOM attribute)
[BUG #8560] back to readOnly but use separate apply
[BUG #8560] Removed the attribute mapping
[BUG #8560] _addAt is now appendAt
[BUG #8560] Use data module instead of setting/getting the data attributes with the attribute API
[BUG #8560] Removed unused _removeAt method
[BUG #8560] Removed MChildrenHandling and replaced all methods with collection methods