Remove the forced default NL code on Customer and Supplier import

This has been introduced since you changed the import/update feature in Sage 200. Previously all customers and suppliers could be imported without a NL code. Now they cannot. Its forcing me to run scripts on every db to remove a default NL code. And for 200 Standard the only way you can do this is via the front end which is far to time consuming. Customers and suppliers do not always have a default NL code. Take Amazon as an example - you can buy pretty much anything off Amazon therefore there is no such thing as a default NL code as every order can be for different items.