issue #2771: add physics files and entries.
issue #2771: add Node::_physicsBody to Node init list
issue #2771: add new line to the end of line.
issue #2771: Change _physicsBody from node to sprite. Reimplement Scene::addChild. Adjust some API.
issue #2771: Fix CI compile errors.
issue #2771: Fix CI compile errors.
issue #2771: Fix CI compile errors.
issue #2771: Add macros to control use physics engine or not
issue #2771:  Change CC_USE_PHYSICS_ENGINE to CC_USE_PHYSICS. Add some implements.
issue #2771:  Add method Scene::createWithPhysics() end Scene::initWithPhysics()
issue #2771:  Add PhysicsTest to TestCpp. Add initTest to TestScene, move Scene::init() from constructor to TestScene::initTest()
Disable log output on release build
Merge guy to 3.0 branch
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into Merge_GUI_to_Develop
Modify scene reader
issue #2771:  Implement the minimum set of physical API. Improve the PhysicsTest
update changelog
Merge pull request #3629 from minggo/develop

[ci skip]update changelog
modify mk files
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into iss2771_physical