Add CREATE_SCENE_FUNC Macro

[giginet]

In common way, we implement createScene method for Layer classes.

This Macro implements the method to get the specific Node as wrapped Scene automatically.

class YourLayer :public cocos2d::Scene
{
  public:
    bool init() override;
    CREATE_SCENE_FUNC(YourLayer);
}

auto scene = YourLayer::createScene();
Director::getIntance()->replaceScene(scene);

[pandamicro]

I think this macro is not very appropriate in the engine, we don't want to predict user's behavior because it's not possible, what do you think ? @zilongshanren

[ricardoquesada]

agreed. I don't think it is needed in the engine.

[zilongshanren]

agreed + 1. We should drop Macros and use template instead.

[pandamicro]

Thanks @ricardoquesada @zilongshanren
@giginet If you think differently, please comment