======== Shortcut key cheet sheet ========
[Basic]
Alt + S: (S)ort
Alt + X: toggle DONE-TODO / toggle (X) mark

[CRUD task]
Alt + A  : (A)dd  task
Alt + C  : (C)opy task
Alt + Del: (D)elete task

[Date]
Alt + W: (W)alk creation date with dialog input
Alt + E: change creation date to tomorrow / walk +1 / the right side of (W) key
Alt + T: change creation date to (T)oday

[Priority]
Alt + P: change (P)riority with dialog input
Alt + J: change priority to next / A→B→C→... / (J) of vim like cursor hjkl
Alt + K: change priority to prev / C→B→A→... / (K) of vim like cursor hjkl
  

======== Specifications ========
[Date field combinations]
Completion  Creation    Status    Note
----------||----------||--------||--------
-           -           Invalid   Because creation-date field must be required in this tool.
-           2019-01-01  TODO      This task was added on 2019-01-01, but not completed yet.
2019-01-01  -           Invalid   Because creation-date field must be required in this tool.
2019-01-01  2019-01-01  DONE1     This task was added on 2019-01-01, and completed on the same day.
2019-01-01  2019-01-02  DONE2     This task was planned to be done on 2019-01-02,
                                  but actually completed on and before the day.
2019-01-02  2019-01-01  DONE3     This task was added on 2019-01-01, and completed on and after the day.

[Data storing]
* Use the local storage(one of client storage your browser has).
  See https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage
* If the url or client changes, the data is not to be accessible.
* Saving timing is on sorting(Alt + S).