Random Unique Code In Invoice

for osCommerce Online Merchant v2.2

In a world where transfer via Bank is common (in my case, Indonesia). Admin need to identify the payment manually. Thus we need a unique identifier to match between payment in bank vs order/Invoice. This adds-Ons is generate 2 digit unique code, you can change the number of unique code I modify this adds on Handling Fee (http://addons.oscommerce.com/info/1190)