provide HTML editor in multichoice (and calculatedmulti) question's answers

Create a new MC question. Verify the HTML editor appears for the choices. Add an image to at least one of the choices. Save the question, and then re-edit it. Verify everything has been saved and re-loaded accurately. Preview the question, and verify that it looks right. Add the question to a quiz. Attempt the quiz as a student one or more times. As teacher go to the quiz responses report and verify the recorded response looks OK. Still as teacher, go to the statistics report and drill down to the details for this question. Verify that the analysis of responses is right. Export the question as Moodle XML. Import to another course. Verify that it has transferred accurately. Export the question as GIFT fomat. Verify that the image is handled in a sensible way. Backup the course with the MC question. Restore to another course. Verify that it has transferred accurately. Edit a MC question that you created before this patch was applied. Make sure it is OK to edit it.