added cpp examples for neuralnets
fixed defects in graph cuts
changes for peer review
remove the eigen3 header files
Merge pull request #2453 from Jiaolong/fix_defects

fixed defects in graph cuts
Scene classification notebook added
notebook polished
added check for opencv version
peer review changes
Merge pull request #2500 from yorkerlin/develop

remove the eigen3 in header files
Merge pull request #2430 from kislayabhi/scene

Scene classification notebook added
Merge pull request #2491 from Jiaolong/graphcuts_peer_review

changes for GSoC peer review
Merge pull request #2499 from khalednasr/neuralnets_cpp_examples

added cpp examples for neuralnets
added functions in SGNDArray