Began work on n-Dimensional Dynamic Time Warping implementation.  Needs testing.
Updated the default distance metric function distance_between to support Vector values.
Updated DTW compute method to accept distance function as optional argument.
Bug fixed: self instead of @self.  Doh!
Bug fix: compute_affinity_multi was building wrong size matrix, using row_size instead of column_size. Fixed.
Updated DTW code to support n-dimensional (vector-valued) observation data.  Template and sample must have same n.