unpaiable invoices are not marked as paid and should also be sent as e-invoice

[vohmar]

If registry is unable to match received payment to any existing unpaid invoice for that particular registrar (indicated by reference nr) new invoice is generated and instantly marked as paid. The invoice is generated with unpayable label and sent to the registrar only via email.

• the unpayable invoice must have receipt date filled. As an additional bonus we might add Paid status on the PDF invoice
• the unpayable invoices should also be sent as e-invoice but these invoices must also have the Payable tag set to NO