Initial commit of sale_invoice_grouping module

review931002

view/party_form.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<data>
+    <xpath expr="/form/notebook/page[@id='sale']" position="inside">
+        <separator string="Invoicing" colspan="4" id="invoicing"/>
+        <label name="sale_invoice_grouping_method"/>
+        <field name="sale_invoice_grouping_method"/>
+    </xpath>
+</data>