As we cannot know which kind of exercise we got on a page in advance due to randomization, make the parameter we send for an answer dependant on the question type we find
Store statistics in a separate page instead of the workflow itself - advantages: * smaller workflow instance - no danger that page is too large for caching, even for large exams. - smaller objects mean also better performance * modification date in exam is not modified when statistics are updated * easier extensible - New function WorkflowPage->childpage easy to use interface for creating child pages - render_submission=exam_protocol: changed name of parameter "-form_objs" to "-filter_form_ids", since form_objs are used typically to keep objects, not ids - Still to do: policy for inclass-exam-statistics.wf