Show timeline ordered by checked date

[jstebenne]

Is your feature request related to a problem? Please describe.
The timeline view only display tasks ordered by the date they were created and there is no way of listing my the date they were checked/done.

Describe the solution you'd like
It would be nice to be able to pass a flag (or something) that would group tasks by the date they were closed.

Additional context
[nothing]

[joeltjames]

I've added this in the attached PR.