Author: Tim Hunt
MDL-31080 quiz editing, must be able to see and delete missing questions
http://git.moodle.org/gw?p=moodle.git;a=commit;h=068384ce651eb26c73f403056e9e9b1513b8acc4
http://github.com/moodle/moodle/commit/068384ce651eb26c73f403056e9e9b1513b8acc4
+ 2.3 en [missingquestion,mod_quiz]