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=b94ea41bbfc478017f3ec7723b387c343f66dc1c
http://github.com/moodle/moodle/commit/b94ea41bbfc478017f3ec7723b387c343f66dc1c
+ 3.5 en [cannotremoveallsectionslots,mod_quiz]
+ 3.5 en [cannotremoveslots,mod_quiz]