Author: Tom Dickman
MDL-65923 core grades: Add a new event for when a grade item is deleted
http://git.moodle.org/gw?p=moodle.git;a=commit;h=68049ac848f0e6cdb7a637a8e5888b5adeceaf5d
http://github.com/moodle/moodle/commit/68049ac848f0e6cdb7a637a8e5888b5adeceaf5d
+ 4.0 en [eventgradeitemdeleted,core_grades]