The following two improvements have been made:
The option of customizing the name of the uploaded file was added.
Spelling mistakes have been corrected and overall language improved.

Added navigation buttons that allow to easily change to previous and next student (with and without submissions) once in a student submission page.
Corrected minor errors.

It is now possible to dynamically generate prefixes using student ids.
Students with no student ids are now matched my name.

We added a new button to the main page.
This new button (named "statistics") allows the user to view an histogram representing grade distribution as well as percentage of submitted solutions, percentage of marked solutions and mean and standard deviation of grade.