iOS: Added new build targets for cocos2d-x and CocosDenshion in order to support C++11 and libC++ properly:
* in a projects, the app and the linked static libs must have been compiled with same version of libC++, otherwise it does not link
Added new class CCSceneGraphTouchDispatcher deriving from CCTouchDispatcher

* Touch dispatching is resolved by visiting the CCNode Graph back to front
CCScrollViewDelegate and CCTableViewDelegate: changed some delegate's methods that used to be pure virtual although there were not mandatory for CCScrollView/CCTableView work
Added new methods on CCScrollView (min/max zoom…)

* only .h for now, .cpp will follow
CCTableView: declared new methods for new features (cell selection and callbacks, reloading data and preserving current scroll pos)
CCBReader.cpp : removed useless include "UIKit/UIDevice.h" that generate build errors because including ObJC definitions inside a pure c++ translation unit
CCControlButton: factorized some code into virtual methods (computeContentSize, layoutTitleLabel) to allow easy subclassing and customization
CCControlSlider: declared method for creating vertical sliders
CCControlSwitch: declared method for creating vertical switch
CCScene: added virtual method onExitWillStart to be called just before transitioning from a scene to another
CCLabelTTF: virtualized updateTexture method to ease subclassing and customization
CCImage: added format GiF
CCImage: declared new static method calculateStringSize
Merge branch 'CCBReader_DOWFixes' into 2.1.5-DOW
Merge branch 'CCControlButton_DoW' into 2.1.5-DOW
Merge branch 'CCControlSlider_DoWExtensions' into 2.1.5-DOW
Merge branch 'CCControlSwitch_DoWExtensions' into 2.1.5-DOW
Merge branch 'CCImage_DoWExtensions' into 2.1.5-DOW
Merge branch 'CCLabel_DoWExtensions' into 2.1.5-DOW
Merge branch 'CCSceneGraphTouchDispatcher' into 2.1.5-DOW