Payments of retained VAT to VAT administration

This issue registers the transactions to/from the VAT office. Declarations and payments are done quarterly up to the 20th of next month. Operation details are registered in an ods file in this repo under accounting/$YEAR/VAT

Start by inspecting the ODS files under accounting/$YEAR/VAT and check how existing VAT transactions are recorded. Register the relevant transactions to and from the VAT office, covering quarterly declarations and payments due by the 20th of the following month. Done means the appropriate year's VAT record is complete and consistent with the existing format.

Written by the indexing model from the issue text.