Added the direct local accumulation for Epanechnikov kernel.
Added the direct local accumulation for Epanechnikov kernel.

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