Fix #549 -- Multiple PDF ticket layouts (#938)

- [x] Data model
- [x] CRUD
- [x] Editor
- [x] Migration from old settings
- [x] Clone files when copying events
  - [x] badges?
- [x] Actual ticket output
- [x] Default layout on event creation
- [x] Link well from ticketing settings
- [x] Tests
- [x] Shipping plugin
  - [x] Migration
  - [x] Settings
  - [x] Create default
- [x] API

src/pretix/plugins/badges/signals.py

@@ -70,6 +70,10 @@ def event_copy_data_receiver(sender, other, item_map, **kwargs):
         bl.pk = None
         bl.event = sender
         bl.save()
+
+        if bl.background and bl.background.name:
+            bl.background.save('background.pdf', bl.background)
+
         layout_map[oldid] = bl
 
     for bi in BadgeItem.objects.filter(item__event=other):