add text orientation property to transcriptions (editable in admin)

closes #850 (closed) #851 (closed) #852 (closed) #853 (closed) #854 (closed) #855 (closed) kind of accidentally because I started fixing the tests that broke

arkindex/documents/migrations/0044_transcription_orientation.py

+# Generated by Django 3.2.6 on 2021-10-22 08:27
+
+import enumfields.fields
+from django.db import migrations
+
+import arkindex.documents.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('documents', '0043_element_creator'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='transcription',
+            name='orientation',
+            field=enumfields.fields.EnumField(default='horizontal-lr', enum=arkindex.documents.models.TextOrientation, max_length=50),
+        ),
+    ]