added BaseError.__repr__ method
renamed old_invalid_models.models.{OldPerson -> Person}
rewritten checking foreignkeys and m2m pointing to missing/abstract models
rewritten checks of ManyToManyField.unique
made RelativeFieldsTests.test_ambiguous_relationship_model green
made RelativeFieldsTests.test_relationship_model_missing_foreign_key green
made RelativeFieldsTests.test_relationship_model_with_foreign_key_to_wrong_model green
made RelativeFieldsTests.test_missing_relationship_model green
made RelativeFieldsTests.test_symmetrical_self_referential_field green
made RelativeFieldsTests.test_too_many_foreign_keys_in_self_referential_model green
made RelativeFieldsTests.test_symmetric_self_reference_with_intermediate_table green