[pylink][bugfix] Fix internal output data storage

See merge request inversemodeling/bayesian-validation!3

The data was dynamically attached to the class object itself.
This data got lost when serializing the object state. Now we make an instance of the nested class and fill it with the data as it should be.

[bayesinference] add valid_metrics option to be passed as a list and parallize the inf_entropy caliculations.