Added support for manual grading and individual feedback
- Lecturers can provide points and feedback comments directly via exam protocol - Grading is allowed, when student has submitted the exam or the exam is not open - Composite questions are graded at the sub-question level - Manual grading have a higher priority than automatic grades - Manual grading/comments can be undone by clearingfield (showing then missing points, automated computed points, ...) - Grades and comments are included in the exam review for students ("Einsicht"). - Grading interactions are implemented as AJAX calls (no need for redrawing the exam protocol, immediate feedback)