Author: Mathew May
MDL-75362 gradebook: add group selector into reports
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ee71eae12a09c1f7121921fa51718b996d90497f
http://github.com/moodle/moodle/commit/ee71eae12a09c1f7121921fa51718b996d90497f
+ 4.1 en [searchgroups,core_grades]