Author: Simey Lameze
MDL-56223 calendar: skip events updating if nothing has changed
http://git.moodle.org/gw?p=moodle.git;a=commit;h=cb5145334d00896b8cc4b6c9df38c919b22322c5
http://github.com/moodle/moodle/commit/cb5145334d00896b8cc4b6c9df38c919b22322c5
+ 3.7 en [eventsskipped,core_calendar]