Model class for SubEvents.
Inheritance: BaseModel, IDataErrorInfo
        /// <summary>
        /// Deletes the specified SubEvent from the list.
        /// </summary>
        /// <param name="s">SubEventModel object to be delted.</param>
        public void DeleteSubEvent(SubEventModel s)
        {
            // SubEvent exists in the database. Remember to delete it later!
            if (s.Id > 0)  this._subEventsToDeleteList.Add(s);
            this._subEventCollection.Remove(s);
            this.NotifyPropertyChanged("SubEventCollection");

            // If list is empty, add a new one since there must be at least one SubEvent.
            if (this._subEventCollection.Count <= 0)
                this.AddNewSubEvent();
        }
        /// <summary>
        /// Adds an empty SubEvent into the list.
        /// </summary>
        public void AddNewSubEvent()
        {
            SubEventModel s = new SubEventModel(new DBLayer.SubEvent());
            s.Name = "";
            s.Start = new DateTime( DateTime.Now.Year, DateTime.Now.Month, (DateTime.Now.Day + 3), 8, 0, 0);
            s.End = new DateTime(DateTime.Now.Year, DateTime.Now.Month, (DateTime.Now.Day + 3), 9, 0, 0);

            this._subEventCollection.Add(s);
            this.NotifyPropertyChanged("SubEventCollection");

            s.VenueId = 1;
            this.UpdateCapacityUI();
        }