Fix #515 -- Add check-in lists (#693)

* Data model and migration

* Some backwards compatibility

* CRUD for checkin lists

* Show and perform checkins

* Correct numbers in table and dashboard widget

* event creation and cloning

* Allow to link specific exports and pass options per query

* Play with the CSV export

* PDF export

* Collapse exports by default

* Improve PDF exporter

* Addon stuff

* Subevent stuff, pretixdroid tests

* pretixdroid tests

* Add CRUD API

* Test compatibility

* Fix test

* DB-independent sorting behavior

* Add CRUD and coyp tests

* Re-enable pretixdroid plugin

* pretixdroid config

* Tests & fixes

src/pretix/plugins/pretixdroid/migrations/0004_auto_20171124_1657.py

@@ -0,0 +1,71 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.2 on 2017-11-24 16:57
+from __future__ import unicode_literals
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+def assign_checkin_lists(apps, schema_editor):
+    AppConfiguration = apps.get_model('pretixdroid', 'AppConfiguration')
+
+    for ac in AppConfiguration.objects.all():
+        cl = ac.event.checkin_lists.get_or_create(subevent=ac.subevent, all_products=True, defaults={
+            'name': ac.subevent.name if ac.subevent else 'Default'
+        })[0]
+        ac.list = cl
+        ac.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('pretixbase', '0077_auto_20171124_1629'),
+        ('pretixdroid', '0003_appconfiguration'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='appconfiguration',
+            name='list',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE,
+                                    to='pretixbase.CheckinList'),
+        ),
+        migrations.AlterField(
+            model_name='appconfiguration',
+            name='all_items',
+            field=models.BooleanField(default=True, verbose_name='Can scan all products'),
+        ),
+        migrations.AlterField(
+            model_name='appconfiguration',
+            name='allow_search',
+            field=models.BooleanField(default=True,
+                                      help_text='If disabled, the device can not search for attendees by name. pretixdroid 1.6 or newer only.',
+                                      verbose_name='Search allowed'),
+        ),
+        migrations.AlterField(
+            model_name='appconfiguration',
+            name='items',
+            field=models.ManyToManyField(blank=True, to='pretixbase.Item', verbose_name='Can scan these products'),
+        ),
+        migrations.AlterField(
+            model_name='appconfiguration',
+            name='show_info',
+            field=models.BooleanField(default=True,
+                                      help_text='If disabled, the device can not see how many tickets exist and how many are already scanned. pretixdroid 1.6 or newer only.',
+                                      verbose_name='Show information'),
+        ),
+        migrations.RunPython(
+            assign_checkin_lists,
+            migrations.RunPython.noop
+        ),
+        migrations.RemoveField(
+            model_name='appconfiguration',
+            name='subevent',
+        ),
+        migrations.AlterField(
+            model_name='appconfiguration',
+            name='list',
+            field=models.ForeignKey(blank=False, null=False, on_delete=django.db.models.deletion.CASCADE,
+                                    to='pretixbase.CheckinList'),
+        ),
+    ]