Bnlearn

* Fix for white/black listing.

Fix for example in spynx

* code refactoring
* bug fix for inference on dag

* df2onehot outputs numerical and one-hot

* update in docstrings
* inferences can now be done with the output of parameter_learning
* added fuction to convert adjmat to BayesianModel (to_BayesianModel)
* Added example of inference
* updates sphnix pages: https://erdogant.github.io/bnlearn/pages/html/Examples.html#start-with-raw-data

* Added new example titanic
* Sprinkler and titanic dataset is downloaded if required
* Added functionality to convert raw dataframe to one-hot datamatrix
* docstring updates
* sphinx updates