Add [##What's this?] in README.md
Create main.cpp
Merge branch 'master' into develop
 - new file:   define.h - define game status
 - new file:   dxutil.h - utilities when using dxlib [no source file]
 - new file:   scene.h -  management scenes

 - new file:   scene.cpp -

TODO:
 - make fade
make fade as transition