by adding related_name to the ContentType ForeignKey. Thanks to Andrew Ingram.
This happened if a polymorphc model used a ContentType ForeignKey.
Plus minor documentation updates.
instead of app-label and model-name (suggested by Ilya Semenov in issue 3).
This is a cleaner and more efficient solution, and applabel/modelname
are not stored redundantly in additional tables any more (the polymorphic models).
This should be the final DB schema now (sorry for any inconvenience).
Also some minor documentation updates.