Merge branch 'warning-clang7' into 'develop'

Modules/Adapters/BoostAdapters/include/otbStringUtils.h

.../Adapters/BoostAdapters/include/otb_boost_expint_header.h

...s/Adapters/BoostAdapters/include/otb_boost_graph_header.h

...ters/BoostAdapters/include/otb_boost_lexicalcast_header.h

...pters/BoostAdapters/include/otb_boost_math_gamma_header.h

...ters/BoostAdapters/include/otb_boost_math_normal_header.h

.../Adapters/BoostAdapters/include/otb_boost_string_header.h

Modules/Adapters/GdalAdapters/include/otbOGRFieldWrapper.hxx

Modules/Adapters/GdalAdapters/include/otbOGRHelpers.h

...Applications/AppClassification/app/otbZonalStatistics.cxx

Modules/Core/Common/src/otbExtendedFilenameHelper.cxx

Modules/Core/Transform/src/otbGeoInformationConversion.cxx

...s/Filtering/MathParser/include/otbBandMathImageFilter.hxx

Modules/Filtering/MathParserX/include/otbParserX.h

...nsionalityReductionLearning/include/otbAutoencoderModel.h

...ing/DimensionalityReductionLearning/include/otbPCAModel.h

...ised/include/otbKNearestNeighborsMachineLearningModel.hxx

...vised/include/otbSharkRandomForestsMachineLearningModel.h

Modules/Learning/Supervised/otb-module.cmake

...Unsupervised/include/otbSharkKMeansMachineLearningModel.h