introducing group hierarchy

src/c3nav/mapdata/migrations/0073_locationgroup_hierarchy.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.8 on 2019-12-21 16:24
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mapdata', '0072_make_wifi_measurement_author_nullable'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='locationgroup',
+            name='hierarchy',
+            field=models.IntegerField(db_index=True, default=0, verbose_name='hierarchy'),
+        ),
+    ]