This does not include user data yet, and it needs more testing.

Conflicts:
	mod/quiz/locallib.php
	mod/quiz/report/overview/overview_table.php
	mod/quiz/report/overview/report.php
	mod/quiz/report/responses/report.php
	question/type/random/questiontype.php

Also, remove automatic redirects to the quiz edit page. Show a message and a button instead.

Except in the question types that have not yet been converted to the new question engine.

This mostly involves moving lang strings around, but I don't have time to do an AMOS script now.

This includes converting behaviours to pluginname strings.

I have reformatted the SQL according to the style used in Moodle code to
improve readability of the query. Added sql_compare_text() to the right
side of the comparison, even though the current callers provide integers
here (just in case).

Every time one column is changed from null to not null
we must ensure that there aren't nulls at all or the
DDL statement will fail, as was reported here. The
simplest way, just apply for the default when the column is null.