CalendarStyle: do not hard code the height of dayOfWeekDelegate

Task-number: QTBUG-39482
Change-Id: I7b610a098402f5ec684fc0d7f9b47c4b9981e733
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
CalendarStyle: do not hard code the width of weekNumberDelegate

Task-number: QTBUG-39482
Change-Id: Ia46f79e5969b9d0a1262bca871a7f389d0df9688
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>