#163 Checked icons improvement

* adds a second star icon on currently unchecked but previously checked entries
   --> can be detected easier for another check run
* simplifies some related code parts
* moves some translation string into message_templates.py
* enables session timeout after 60 minutes
* improves comment card layout sizing
* adds/updates translations

konova/models/object.py

@@ -408,6 +408,20 @@ class CheckableObjectMixin(models.Model):
         self.log.add(action)
         return action
 
+    def get_last_checked_action(self):
+        """ Getter for the most recent checked action on the log
+
+        Returns:
+            previously_checked (UserActionLogEntry): The most recent checked action
+        """
+        from user.models import UserAction
+        previously_checked = self.log.filter(
+            action=UserAction.CHECKED
+        ).order_by(
+            "-timestamp"
+        ).first()
+        return previously_checked
+
 
 class ShareableObjectMixin(models.Model):
     # Users having access on this object