Allow to select the customer bank account used for sepa payments
In case the customer has more than one valid mandate the first one is always used but sometimes the customer may request to use another one.
Currently the sepa_mandate is already stored on the payment but is not possible to set them. I propose to show the field on the view so the user can choose an specific mandate before processing the payments. If the value is not set the current behaviour will be keep.
In order to easly choose the mandate to be used I think the account number should be included on the mandate rec_name so its easier to select the correct mandate.