Decision Tree Notebook started
typos fixed, final exercise plot fixed
minor change in last code snippet
Merge pull request #2097 from mazumdarparijat/pca

Decision Tree Notebook started
data submodule updated
NEWS update
Merge pull request #2099 from mazumdarparijat/pca

data submodule update and NEWS update
Added multilabel reader in LibSVMFile.
Added multilabel writer in LibSVMFile. Updated LibSVMFile unit test.
Corrected indent issues and memory leak.