sale_usability: add a wizard to write discount on all lines

The wizard is available under the "Action" menu. It has an option to
apply only on product or service lines.

Add a button "Send ack by email" on confirmed sale.order

sale_usability/views/sale_order.xml

@@ -32,6 +32,9 @@
         <xpath expr="//field[@name='order_line']/tree/field[@name='product_template_id']" position="after">
             <field name="product_barcode" optional="hide"/>
         </xpath>
+        <button name="action_quotation_send" attrs="{'invisible': ['|', ('state', '=', 'draft'), ('invoice_count','&gt;=',1)]}" position="before">
+            <button name="action_quotation_send" type="object" string="Send Order Acknowledgement" attrs="{'invisible': ['|', ('state', 'not in', ('sale', 'done')), ('invoice_count','&gt;=',1)]}"/>
+        </button>
     </field>
 </record>