Automatic question numbering when editing questions

When you delete a question from a questionnaire, the other questions keep their question number. So you get gaps in the order. You can also change question numbers to already existing ones.

Changing a question number should ripple through the rest. If you change nr. 5 to nr. 2, then nrs. 2, 3, and 4 should automatically change to 3, 4, and 5.

When you delete a question, all subsequent questions should move up 1 place.