Changes:
- new syntax for command line tool
- Python bindings for basic functionality
- removed multiprocessing support for k-NN (it only improved performance
for large validation sets, which we do not need) - simpler output from the command line tool
Code changes:
- restructured main.rs and estimation routines
- all estimators now implement the trait BayesEstimator
- NN and NNBound are estimators on their own