[8.0] account_voucher_killer

This module is migrated from OCA/bank-statement-reconcile 7.0.

As it's purpose is to remove the Pay buttons from the invoice forms, it is related to payment. 
This bank-payment repository is therefore a better place for it.

Since bank statements do not use vouchers in 8.0, this module is even more useful than in 7.0.

The module migrates trivally from 7.0.
This must be of the same length of the title string, or Odoo RST parser will complain