Author: James Pratt
MDL-41758 quiz statistics : link to full break down of stats for slots
where a question in a slot has subquestions and/or variants.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=51e3ded838e78bb5ffc751213fbd4cf704c79f22
http://github.com/moodle/moodle/commit/51e3ded838e78bb5ffc751213fbd4cf704c79f22
+ 2.7 en [slotstructureanalysis,quiz_statistics]