add a latest method to query the latest x events

src/mahjong_ranking/models.py

@@ -56,7 +56,7 @@ class EventRanking(models.Model):
         )
         sum_placement = 0.0
         sum_score = 0.0
-        event_hanchans = Hanchan.objects.confirmed_hanchans(
+        event_hanchans = Hanchan.objects.confirmed(
             user=self.user_id,
             event=self.event_id
         )
@@ -441,7 +441,7 @@ class KyuDanRanking(models.Model):
         Fetches all valid Hanchans from this Player and recalculates his
         Kyu/Dan Ranking.
         """
-        valid_hanchans = Hanchan.objects.confirmed_hanchans(user=self.user)
+        valid_hanchans = Hanchan.objects.confirmed(user=self.user)
         valid_hanchans = valid_hanchans.order_by('start')
         if since and self.last_hanchan_date and since < self.last_hanchan_date:
             force_recalc = True