Author: Michael Aherne
MDL-41895 conditions Show details of grouping restriction
http://git.moodle.org/gw?p=moodle.git;a=commit;h=195a68a508ae74e60d6bd418bbaad8ab32a05a26
http://github.com/moodle/moodle/commit/195a68a508ae74e60d6bd418bbaad8ab32a05a26
+ 2.6 en [requires_grouping,core_condition]