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=7328144c9ddb9ef9fcf601f67cb30e4a51a9fdd3
http://github.com/moodle/moodle/commit/7328144c9ddb9ef9fcf601f67cb30e4a51a9fdd3
+ 4.0 en [dayeventsmany,core_calendar]
+ 4.0 en [dayeventsnone,core_calendar]
+ 4.0 en [dayeventsone,core_calendar]