Remove warnings in the source code

.gitignore

.gitlab-ci.yml

CMakeLists.txt

src/CMakeLists.txt

src/classification/ConvexHull1D.cpp

src/classification/ConvexHull1D.hpp

src/classification/LPWrapper.cpp

src/classification/LPWrapper.hpp

src/classification/SVMWrapper.cpp

src/classification/SVMWrapper.hpp

src/classification/prop_sorted_d_mat.cpp

src/descriptor_identifier/model/Model.cpp

src/descriptor_identifier/model/Model.hpp

src/descriptor_identifier/model/ModelClassifier.cpp

src/descriptor_identifier/model/ModelClassifier.hpp

src/descriptor_identifier/model/ModelLogRegressor.cpp

src/descriptor_identifier/model/ModelLogRegressor.hpp

src/descriptor_identifier/model/ModelRegressor.cpp

src/descriptor_identifier/model/ModelRegressor.hpp

src/descriptor_identifier/solver/SISSOClassifier.cpp