Feature Adders should handle intermediate features

[AlexisMignon]

WHAT:
In the current implementation, a feature which depends on the presence of other features which are not in the list feature_names or not in the original features retrieved from the database cannot be built. It should be possible to build intermediate features which are not kept in the end but necessary to build other features.

HOW:
The feature dispatcher analyses which feature adder can deal with the requested features. During this analysis, features which are in the requirements of a feature adder but not in the list of feature names will be added to the list of features to be built and removed once all the demanded features are built.

TEST:
Require a feature that depends on a missing feature.