[mkcal] Fix ExtendedCalendar::rawExpandedEvents() to return all events between interval

KDateTime(end, ts).addSecs() was used to set day end. The ctor, however,
creates a date-only instance, for which adding seconds less than a day
is a no-op.
Merge pull request #12 from pvuorela/master

[mkcal] Fix ExtendedCalendar::rawExpandedEvents() to return all events b...