Fix #708 -- Standardize use of check-in (#711)

* standardize use of check-in

* split on occurrence of "checkin_*"

Instead of skipping when encountering "checkin_*", we now split and only
pass the second part to the spell-checker. This fixes the aforementioned
problem.

* fix spelling issue with checkins

src/pretix/base/models/checkin.py

@@ -100,7 +100,7 @@ class CheckinList(LoggedModel):
 
 class Checkin(models.Model):
     """
-    A checkin object is created when a person enters the event.
+    A check-in object is created when a person enters the event.
     """
     position = models.ForeignKey('pretixbase.OrderPosition', related_name='checkins')
     datetime = models.DateTimeField(default=now)

src/pretix/base/models/items.py

@@ -179,7 +179,7 @@ class Item(LoggedModel):
     :type max_per_order: int
     :param min_per_order: Minimum number of times this item needs to be in an order if bought at all. None for unlimited.
     :type min_per_order: int
-    :param checkin_attention: Requires special attention at checkin
+    :param checkin_attention: Requires special attention at check-in
     :type checkin_attention: bool
     """