issue #5161, replace all _size to _contentSize
issue #5161, deprecated getSize
refactor setSize to setContentSize and deprecated the old interface
fix contentSize not set properly problem
Merge branch 'v3' into feature5161

Conflicts:
	cocos/editor-support/cocostudio/CCSGUIReader.cpp
	cocos/editor-support/cocostudio/WidgetReader/ButtonReader/ButtonReader.cpp
	cocos/editor-support/cocostudio/WidgetReader/ImageViewReader/ImageViewReader.cpp
	cocos/editor-support/cocostudio/WidgetReader/LoadingBarReader/LoadingBarReader.cpp
	cocos/editor-support/cocostudio/WidgetReader/WidgetReader.cpp
	tests/cpp-tests/Classes/UITest/CocoStudioGUITest/UIListViewTest/UIListViewTest.cpp
issue #5161, replace deprecated methods
issue #5161, replace _size with _contentSize
Merge pull request #7190 from minggo/perf-improve

use reference instead
Merge pull request #7189 from andyque/feature5161

replace size with contentSize