GradeTypes now have weights
the points of a Grade are calculated based on the mark and the weight of
the type
added controller functionality to add new Subjects and GradeTypes
Edit and remove Target added
PointTarget can now be evaluated

New Subjects or GradeTypes have to be added via the method in the
EnterGrade/SetTarget controller and are no longer added automatically!!!
addNewPointTarget implemented
editPointTarget implemented