Teacher activity - browsing student submissions

[adhameer]

Once the due date of an exercise has passed, we would like to manually screen our students' submissions with help from the automatically generated grading reports. Currently this requires us to have the Teacher view open and manually double-click each token, then select the correct exercise. It would be much more convenient to be able to navigate through all submissions in the student view, e.g. with Back and Forward buttons that could be used to cycle through all tokens.