Author: Tim Hunt
MDL-20636 Finish conversion of the Opaque qtype/behaviour.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2eeb76f845c23bdb5359623445a8062c7888b7cd
http://github.com/moodle/moodle/commit/2eeb76f845c23bdb5359623445a8062c7888b7cd