[IMP] mail: uniformize deadline naming in activities, let us use deadline everywhere

addons/mail/models/mail_activity.py

@@ -65,7 +65,7 @@ class MailActivity(models.Model):
     icon = fields.Char('Icon', related='activity_type_id.icon')
     summary = fields.Char('Summary')
     note = fields.Html('Note')
-    date_deadline = fields.Date('Due Date', index=True, required=True, default=fields.Date.today)
+    date_deadline = fields.Date('Deadline', index=True, required=True, default=fields.Date.today)
     # description
     user_id = fields.Many2one(
         'res.users', 'Assigned to',

addons/mail/views/mail_activity_views.xml

@@ -102,7 +102,7 @@
                         help="Show all records which has next action date is before today"/>
                 <separator/>
                 <group expand="0" string="Group By">
-                    <filter string="Due Date" context="{'group_by': 'date_deadline'}"/>
+                    <filter string="Deadline" context="{'group_by': 'date_deadline'}"/>
                     <filter string="Created By" context="{'group_by': 'create_uid'}"/>
                     <filter string="Activity Type" context="{'group_by': 'activity_type_id'}"/>
                 </group>