#35 Sanity command

* refactors "toggling" of recorded/checked state
* introduces mark_as_edited() for RecordableObjectMixin

ema/models/ema.py

@@ -7,6 +7,7 @@ Created on: 15.11.21
 """
 import shutil
 
+from django.contrib.auth.models import User
 from django.db import models
 from django.db.models import QuerySet