Ability to filter out Discount Line Item
At present, there is no way to filter or adjust the XML when it is sent to Ship Station. In many cases, one may wish to update this data before it is sent or remove the Discount Line Item. Adding a filter immediately before appending the XML in class-wc-shipstation-api-export.php (ca. line 293) would allow developers to filter data before it is appended to the request.