Assing Salesman to Incvoies

To calculate commissions due properly to each salesman, it will be more flexible if salesman can be changed at order entry time. Currently salesman is allocated by customer brach, but will be more flexible if we can change the salesman for an invoice at ConfirmDispatch_Invoice.php, to point the correct salesman. In most retail business a "cash customer" is created, so we'll need to know hoe the salesman was.