* Fix in PositionChildLayout.
* Added clipping for the button interior.
* Renamed m_CompositionLayout to view_layout_
* Remove ComputeLayout2
* Remove ComputePosition2
* Renaming of signals in Button class
* "clicked" signal became "click"
* "changed" signal became "state_changed"
* Replaced ComputeChildLayout with ComputeContentSize
* Replaced PositionChildLayout with ComputeContentPosition
* Replaced STATE_PRESSED with VISUAL_STATE_PRESSED 
* Replaced STATE_NORMAL with VISUAL_STATE_NORMAL
* Replaced STATE_PRELIGHT with VISUAL_STATE_PRELIGHT
* Replaced STATE_DISABLED with VISUAL_STATE_DISABLED