removed lru_cache to vectorizer, and re-arranged the code now that static methods are not needed any more
restored Exception conversion, since it was part of the validation coded inside the validator.
All the concept must be re-considered together soon
We do not accept any more single data points as arguments for fit or transform.
removed cache-dependency on features evaluator, and fixes tests referred to that
removed settings files since they were about cache stuff only
Merge branch 'remove-ram-cache' into develop