A "reassign graders" button

Whenever the graders workload is changed, it does not affect existing grader assignments. I would prefer to keep it that way. However, one might want to reassign graders according to the new distribution. There should be a button that does just that.

Reassigned submissions should be equally distributed with the respect to the submission time. That is, one grader should not receive all the earliest submissions, whereas another gets all the latest.