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/ticketoutputpdf/forms.py

@@ -0,0 +1,41 @@
+from django import forms
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.models import CachedCombinedTicket, CachedTicket
+
+from .models import TicketLayout, TicketLayoutItem
+
+
+class TicketLayoutForm(forms.ModelForm):
+    class Meta:
+        model = TicketLayout
+        fields = ('name',)
+
+
+class TicketLayoutItemForm(forms.ModelForm):
+    class Meta:
+        model = TicketLayoutItem
+        fields = ('layout',)
+
+    def __init__(self, *args, **kwargs):
+        event = kwargs.pop('event')
+        super().__init__(*args, **kwargs)
+        self.fields['layout'].label = _('PDF ticket layout')
+        self.fields['layout'].empty_label = _('(Event default)')
+        self.fields['layout'].queryset = event.ticket_layouts.all()
+        self.fields['layout'].required = False
+
+    def save(self, commit=True):
+        if self.cleaned_data['layout'] is None:
+            if self.instance.pk:
+                self.instance.delete()
+            else:
+                return
+        else:
+            return super().save(commit=commit)
+        CachedTicket.objects.filter(
+            order_position__item_id=self.instance.item, provider='pdf'
+        ).delete()
+        CachedCombinedTicket.objects.filter(
+            order__positions__item=self.instance.item
+        ).delete()