Add method to close all invoices with an invoice direct

When the charge_members_manually option is active there is no need for an
explicit balancing step. This new function allows to close_direct all
orders which have an assigned invoice, which is usually indication enough
to find orders which can be closed finally.

config/locales/de.yml

@@ -712,6 +712,8 @@ de:
       close:
         alert: 'Ein Fehler ist beim Abrechnen aufgetreten: %{message}'
         notice: Bestellung wurde erfolgreich abgerechnet, die Kontostände aktualisiert.
+      close_all_direct_with_invoice:
+        notice: Es wurden %{count} Bestellung abgerechnet.
       close_direct:
         alert: 'Bestellung kann nicht abgerechnet werden: %{message}'
         notice: Bestellung wurde abgerechnet.
@@ -733,6 +735,7 @@ de:
         total_fc: Summe (FC-Preis)
         units: Einheiten
       index:
+        close_all_direct_with_invoice: Alle mit Rechnung abrechnen
         title: Beendete Bestellungen
       invoice:
         edit: Rechnung bearbeiten

config/locales/en.yml

@@ -737,6 +737,8 @@ en:
       close:
         alert: 'An error occured while accounting: %{message}'
         notice: Order was settled succesfully, the balance of the account was updated.
+      close_all_direct_with_invoice:
+        notice: '%{count} orders have been settled.'
       close_direct:
         alert: 'Order can not be settled: %{message}'
         notice: Order was settled.
@@ -758,6 +760,7 @@ en:
         total_fc: Sum (FC-price)
         units: Units
       index:
+        close_all_direct_with_invoice: Close all with invoice
         title: Closed orders
       invoice:
         edit: Edit invoice