Adds setNormalizedPosition()

Changes in `visit()` were done in order to do it
in a robust and fast way.
Little fixes for setNormalized
Compiles on iOS
Merge remote-tracking branch 'cocos2d/v3' into normalized_position

Conflicts:
	CHANGELOG
	cocos/ui/UILayout.cpp
Lua compiles and runs
Compiles on Windows and Android
ouch, more windows compile issues
Merge pull request #6947 from ricardoquesada/normalized_position

Adds setNormalizedPosition()