Author: Shamim Rezaie
MDL-61115 mod_lesson: Lesson overrides to observe group membership
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5d165234221a11e98113f286d9af1b10a98994bf
http://github.com/moodle/moodle/commit/5d165234221a11e98113f286d9af1b10a98994bf
+ 3.5 en [groupsnone,mod_lesson]