Reverting K-Means ordering. It could be re-added as a post-processing step later.
Adjusting edge cases in Mahalanobis and Bhattacharyya distance calculations.
Updating Gaussian Mixture models to provide log-domain computations.
Correcting Determinant and LogDeterminant implementation when the given matrix is symmetric but not positive definite.
Adding specialized Kd-Tree methods to return just the closest neighbor in a query.
Attempting to normalize more unit tests due to differences in sorting algorithms.
Merge branch 'development' into portable

Conflicts:
	Sources/Accord.MachineLearning/Clustering/KMeans.cs
	Sources/Accord.MachineLearning/Structures/KDTree`1.cs
Corrections of PCL code due to recent updates of main repository