Fix XML import/export of Essay questions

1. Create a course.
2. Create some essay questions with different values for all the new essay options
3. * The 4 different input types.
4. * Without, or with different numbers of attachemnts.
5. * Different input area sizes.
6. * With and without grader info.
7. Export these questions in Moodle XML format.
8. Import into a new course.
9. Compare the original and imported questions by opening their editing forms side-by-side, and verify that all the settings have been copied accurately.

For extra credit:

1. Export an essay from a Moodle 2.0 site.
2. Verify that importing it into 2.1 sets all the defaults correctly (Input type editor, 15 lines, no attachments, no grader info).