ENH: Add BoostMachineLearningModel functionnalities.

...lassification/otbTrainMachineLearningImagesClassifier.cxx

Code/UtilitiesAdapters/OpenCV/otbBoostMachineLearningModel.h

...UtilitiesAdapters/OpenCV/otbBoostMachineLearningModel.txx

...tiesAdapters/OpenCV/otbBoostMachineLearningModelFactory.h

...esAdapters/OpenCV/otbBoostMachineLearningModelFactory.txx

...ilitiesAdapters/OpenCV/otbMachineLearningModelFactory.txx

Testing/Code/Learning/CMakeLists.txt

Testing/Code/Learning/otbLearningTests6.cxx

Testing/Code/Learning/otbMachineLearningModelCanRead.cxx

Testing/Code/Learning/otbTrainMachineLearningModel.cxx