Author: Tim Hunt
MDL-74752 qtypes gapselect & ddwtos: implement regrading hooks
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5990158a6fc3d8f053b293a32fc427d3bfa2d2b4
http://github.com/moodle/moodle/commit/5990158a6fc3d8f053b293a32fc427d3bfa2d2b4
+ 4.0 en [regradeissuenumchoiceschanged,qtype_gapselect]
+ 4.0 en [regradeissuenumgroupsschanged,qtype_gapselect]