Merge branch 'app_engine_flags' into 'develop'

...tions/AppClassification/app/otbDSFuzzyModelEstimation.cxx

...cations/AppClassification/app/otbKMeansClassification.cxx

...tions/AppClassification/app/otbMultiImageSamplingRate.cxx

...lications/AppClassification/app/otbOGRLayerClassifier.cxx

...pplications/AppClassification/app/otbSampleExtraction.cxx

...Applications/AppClassification/app/otbSampleSelection.cxx

...ations/AppClassification/app/otbTrainImagesClassifier.cxx

...Applications/AppClassification/app/otbTrainRegression.cxx

...pplications/AppClassification/app/otbVectorClassifier.cxx

...tions/AppClassification/app/otbVectorDataDSValidation.cxx

.../Applications/AppClassification/include/otbTrainBoost.txx

...ations/AppClassification/include/otbTrainDecisionTree.txx

...AppClassification/include/otbTrainGradientBoostedTree.txx

...ications/AppClassification/include/otbTrainImagesBase.txx

...es/Applications/AppClassification/include/otbTrainKNN.txx

...Applications/AppClassification/include/otbTrainLibSVM.txx

...tions/AppClassification/include/otbTrainNeuralNetwork.txx

...tions/AppClassification/include/otbTrainRandomForests.txx

...es/Applications/AppClassification/include/otbTrainSVM.txx

.../AppClassification/include/otbTrainSharkRandomForests.txx