Teacher can edit submission (of his quizes) and determine which answers are correct

[josemvidal]

• [ ] show all answers given, along with the correct answer
• [ ] teacher can mark each one correct or not, even the ones that were auto-graded #55
• [ ] after a teacher has graded a submission, it is marked as graded. This mark shows in the list of submissions, so the teacher knows not to grade it again.

[jeSager]

Edit grade button exists, but is currently disabled.

Will work with next update.