Author: Shamim Rezaie
MDL-68444 calendar: Improve how screenreaders read day titles
Screenreaders now know if each day has any event or not
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0368c8e2a8e18e46480984e0459a8676ed9dd01a
http://github.com/moodle/moodle/commit/0368c8e2a8e18e46480984e0459a8676ed9dd01a
+ 3.8 en [dayeventsmany,core_calendar]
+ 3.8 en [dayeventsnone,core_calendar]
+ 3.8 en [dayeventsone,core_calendar]