Add updated classification scheme to optimization

src/classification/ConvexHull1D.cpp

src/classification/ConvexHull1D.hpp

src/descriptor_identifier/Model/Model.cpp

src/descriptor_identifier/SISSO_DI/SISSORegressor.cpp

src/feature_creation/feature_space/FeatureSpace.cpp

src/feature_creation/node/ModelNode.cpp

src/nl_opt/NLOptWrapper.cpp

src/nl_opt/NLOptWrapper.hpp

src/python/descriptor_identifier/SISSOLogRegressor.cpp