_2012-08-15_
* Added density estimation trees, found in src/mlpack/methods/det/.
* Added non-negative matrix factorization, found in src/mlpack/methods/nmf/.
* Added experimental cover tree implementation, found in
src/mlpack/core/tree/cover_tree/ (157).
* Better reporting of boost::program_options errors (225).
* Fix for timers on Windows (212, 211).
* Fix for allknn and allkfn output (204).
* Sparse coding dictionary initialization is now a template parameter (220).