Invoices can now show the original sales order line's number instead of renumbering every invoice back to 1, 2, 3. So a partial invoice covering sales order lines 3, 5, and 8 shows exactly that: 3, 5, 8, on screen, on the PDF, and when adding lines from the sales order. It's a simple option to turn on, and it matches how packing slips already work.
