ENH: resolve issues from code review

...Applications/AppClassification/app/otbImageClassifier.cxx

Modules/Applications/AppClassification/test/CMakeLists.txt

...ing/LearningBase/include/otbImageClassificationFilter.hxx

...rning/Supervised/include/otbBoostMachineLearningModel.hxx

...upervised/include/otbDecisionTreeMachineLearningModel.hxx

...ed/include/otbGradientBoostedTreeMachineLearningModel.hxx

...ised/include/otbKNearestNeighborsMachineLearningModel.hxx

...ning/Supervised/include/otbLibSVMMachineLearningModel.hxx

...pervised/include/otbNeuralNetworkMachineLearningModel.hxx

...Supervised/include/otbNormalBayesMachineLearningModel.hxx

...earning/Supervised/include/otbSVMMachineLearningModel.hxx

...vised/include/otbSharkRandomForestsMachineLearningModel.h

...sed/include/otbSharkRandomForestsMachineLearningModel.hxx

...supervised/include/otbSharkKMeansMachineLearningModel.hxx