to improve an iteration process of recognizing new properties #6
Description
https://differ.readthedocs.org/en/latest/#id35
It is difficult to observe all properties that metadata extractors offer.
So it is possible that some of properties remain unrecognized and they are not never used.
It would be great to offer some debug mode when an application shows all unused properties.
At the end of an iteration (ie. configuration) an application will show no unused property.