Adding parameterless constructors for statistical distributions and expanding unit tests.
Updating Mode calculation so an optimum method is chosen depending on whether the provided data values implement IComparable.
Updating error-based pruning to avoid computing modes when there are no elements covered by a node.
Updating K-Modes to select modes per column, instead of entire elements. This also enables the use of the Kmeans++ initialization scheme in KModes.
Merge remote-tracking branch 'upstream/development' into development
Merge branch 'development' into portable

Conflicts:
	Sources/Accord.MachineLearning/Clustering/KModes`1.cs
	Sources/Accord.MachineLearning/DecisionTrees/DecisionNode.cs