refactor UILayoutExecutant to LayoutManager
rename UILayout
Executant.h to UILayoutManager.h
Merge pull request #6914 from andyque/refactorLayoutExecutant

refactor:  rename UILayoutExecutant to UILayoutManager
[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #6917 from CocosRobot/update_cocosfiles_1401256188

[AUTO][ci skip]: updating cocos2dx_files.json
remove keyboard notifications from NSNotificationCenter
invalidate NSTimer instance in destroy to prevent memory leak
Merge pull request #6918 from minggo/fix-object-leak

Fix NSNotificationCenter and NSTimer leaks
[ci skip]
coding style fix
Merge pull request #6921 from minggo/code-fix

coding style fix
fix mingw32/mingw64 build: use system libs and includes rather than prebuilt ones.
Merge branch 'mingw-build' of github.com:John-He-928/cocos2d-x into mingw-build