added order in daily planning based on officeAvailability which considers holidays, extra_availabilities, general appointments from Appointment, and subject assesments from AppointmentTypeLink

removed appointments reference from model. Filter out extra availabilities for the method is_on_leave

Issue #239 Removed get_details method and changed extend_context method to use Worker.get_by_user. Enhancement: now the superuser also shows a name in the upper right corner or its username if no full_name is available.