adjusted for .NET Frame 4.0
added optional capacity to Registry constructor
added Learn() method to BayesBase
completely removed dependencies on IReadOnlyCollection and added Learn() function to BayesBase
added TrainedWith extension method for bayes classifiers
added OptimizedNaiveBayesClassifier using lookups, however both classifiers tend to return very edgy results at the moment ... a bug?
added another example to point out the problem
added distinct observation tracking to the corpus registry
allowed external access to distinct observation set