Better handling of extra answer space
Right now the extra answer space does not play a special role in the workflow, being just a separate Problem
instance.
By extending the yaml format (#31 (closed)), we could specify that some of the scanned boxes are not corresponding to Solution
s, and so shouldn't be graded. Further, assuming we implement checkboxes (#17 (closed)) we could add a checkbox "see extra" to every answerbox and if the students tick that box, we could append the bonus space to the image.