MDL-43749 DO NOT USE! quiz database upgrade code

Here is the database upgrade code for this issue. However, don't use it
because I have only done the database upgrade part. I have not changed
the code that uses this data, so applying this patch will break your
site.

I have only committed and pushed this for these reasons:
* I wanted an off-site backup.
* If anyone would like to review these changes, then I would love to get
the feedback.
MDL-43749 quiz DB tables. Put install.xml in a more logical order.

All settings tables before all user data.
MDL-43749 document the changes.
MDL-43749 very rought work-in-progress.
More clean-up.
MDL-43749 more elimination of quiz->questions.

So far, this seem to be removing more code than it is adding.

Just mod/quiz/ editlib.php, edit.php and attemptlib.php to go.