Add Grading to Overview Screen

[Jeremy Hopkins]

Would it be possible to add the ability to enter the tutor grade to the overview screen so that the “group grade out of 100” could be added via the first screen?

This is because academics will often be copying grades in from other sources, being able to do it in one screen would be helpful.

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[Frédéric Massart]

Add support for grading from the overview screen. Fixes #33

→ <<cset 770fe7a8abe8>>