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=a092131b7305a459f11e0b96e658e9df96aee4b8
http://github.com/moodle/moodle/commit/a092131b7305a459f11e0b96e658e9df96aee4b8
+ 3.9 en [dayeventsmany,core_calendar]
+ 3.9 en [dayeventsnone,core_calendar]
+ 3.9 en [dayeventsone,core_calendar]