Add tests for new MahalanobisDistance constructor.
Add tests for new MahalanobisDistance constructor.


BookChan/mlpack,trungda/mlpack,palashahuja/mlpack,thirdwing/mlpack,bmswgnp/mlpack,BookChan/mlpack,stereomatchingkiss/mlpack,chenmoshushi/mlpack,Azizou/mlpack,chenmoshushi/mlpack,ajjl/mlpack,theranger/mlpack,ranjan1990/mlpack,trungda/mlpack,thirdwing/mlpack,ranjan1990/mlpack,thirdwing/mlpack,ersanliqiao/mlpack,ajjl/mlpack,Azizou/mlpack,minhpqn/mlpack,theranger/mlpack,stereomatchingkiss/mlpack,palashahuja/mlpack,palashahuja/mlpack,ersanliqiao/mlpack,datachand/mlpack,trungda/mlpack,lezorich/mlpack,theranger/mlpack,BookChan/mlpack,minhpqn/mlpack,darcyliu/mlpack,darcyliu/mlpack,chenmoshushi/mlpack,ersanliqiao/mlpack,stereomatchingkiss/mlpack,Azizou/mlpack,datachand/mlpack,erubboli/mlpack,minhpqn/mlpack,lezorich/mlpack,bmswgnp/mlpack,erubboli/mlpack,erubboli/mlpack,darcyliu/mlpack,ranjan1990/mlpack,lezorich/mlpack,ajjl/mlpack,bmswgnp/mlpack,datachand/mlpack