Simulate changes in past courses grades

[noabarlia]

As a user, I would like to be able to simulate changes in my past courses' grades and to see the outcome of the change in analytics. This could help a student to determine if he should retake a course.
I think this will be very helpful, as for some students grades are a major consideration when planning a degree.

[ScDor]

This implies we store and manage grade data, but I'm not aware we do, please change this issue/create another to define what data is being saved and where (my guess would be in Take), where it's shown and how it's used