Intro nb added
clean up and regression
preprocessor example
some more additions
revamp structure
some cleanups
more cleanups
fixed memory leak in graph cut unit test
memory leaks fixed.
Merge pull request #2340 from khalednasr/autoencoders

Implemented denoising autoencoders
Merge pull request #2341 from Jiaolong/graph_cut

fixed memory leak in graph cut unit test
Merge pull request #2342 from kislayabhi/unittest_old_lda

memory leaks fixed in LDA unittest
update krr example
Merge pull request #2244 from Saurabh7/intronb

Intro nb added
Implemented contractive autoencoders