Fix some template errors uncovered by the last ekklesia-common change

Missing cell attributes were suppressed before, which masked these
errors.

src/ekklesia_portal/concepts/argument_relation/argument_relation_cells.py

@@ -20,9 +20,15 @@ def show_voting(self):
     def show_ca_button(self):
         return  # self.current_user is not None
 
+    def title(self):
+        return self.proposition_title
+
     def vote(self):
         return self._model.user_vote(self.current_user)
 
+    def num_counter_arguments(self):
+        return 0
+
     def proposition_url(self):
         return self.link(self._model.proposition)
 

src/ekklesia_portal/concepts/argument_relation/templates/argument_relation.j2.jade

@@ -35,7 +35,6 @@
     .argument_relation_actions
       .counter_arguments
         if show_ca_button
-          num_counter_arguments = counter_arguments|length
           a.counter_arguments_btn(href="#")
             strong.large_number= num_counter_arguments
             | 

src/ekklesia_portal/concepts/proposition/templates/detail_top/proposition_detail_top_draft.j2.jade

@@ -22,7 +22,7 @@
         a(href=become_submitter_url)= become_submitter_url
 
     if valid_submitter_invitation_key and not current_user_is_submitter
-      p = _('invited_to_become_submitter')
+      p= _('invited_to_become_submitter')
 
       if current_user
         form.become_submitter_form(action=become_submitter_action, method="POST")