It's only necessary in the exam view, as the approach in the grade view
is different

 - Remove panel from EditPanel/FeedbackBlock, must be left to
 implementer to use it where needed (not in Exam.jsx, for example)
 - Removed is-active from feedback option blocks
 - Add text saying that the section below it shows feedback options

This still crashes on problem deletion, but fixes regular use.
You can also switch exams and everything.

This is a sub-optimal fix, could be adjusted later on.