PotentialNamespace is feature namespace extracted while detecting
features in layer. It will server for special feature detector. The
current detectors return empty namespace.
1. Featurefmt testing code is moved to featurefmttest package.
2. Featurefmt now can be tested against a csv file, which contains the
expected package information result.
Main Clair logic is changed in worker, updater, notifier for better adapting
ancestry schema. Extensions are updated with the new model and feature lister
and namespace detector drivers are able to specify the specific listers and
detectors used to process layer's content. InRange and GetFixedIn interfaces
are added to Version format for adapting ranged affected features and next
available fixed in in the future. Tests for worker, updater and extensions
are fixed.
