Flutter/dir構成

参考

https://qiita.com/tanakeiQ/items/2c4a7fcb8e95b9aa55ad

https://issus.me/projects/1520/issues/35

blok参考

https://github.com/felangel/bloc/tree/master/examples/flutter_todos/lib

https://github.com/vaygeth89/reactive_flutter_todo_database_app/tree/master/lib