Author: Ferran Recio
MDL-78283 core_courseformat: group mode dropdown
http://git.moodle.org/gw?p=moodle.git;a=commit;h=6e1fff1a573e30c90285c37a4e3fe950276535cb
http://github.com/moodle/moodle/commit/6e1fff1a573e30c90285c37a4e3fe950276535cb
+ 4.3 en [groupmode_groupsseparate_help,core_group]
+ 4.3 en [groupmode_groupsvisible_help,core_group]