Author: Shamim Rezaie
MDL-65399 mod_quiz: UI should prevent deleting the last slot of section
http://git.moodle.org/gw?p=moodle.git;a=commit;h=aa6a8b98c67a80d983b547f17914bc4b48c399b9
http://github.com/moodle/moodle/commit/aa6a8b98c67a80d983b547f17914bc4b48c399b9
+ 3.7 en [cannotremoveallsectionslots,mod_quiz]
+ 3.7 en [cannotremoveslots,mod_quiz]