ENH : add formulas

...eatureExtraction/otbAngularSecondMomentumTextureFunctor.h

Code/FeatureExtraction/otbClusterProminenceTextureFunctor.h

Code/FeatureExtraction/otbClusterShadeTextureFunctor.h

Code/FeatureExtraction/otbContrastTextureFunctor.h

Code/FeatureExtraction/otbCorrelationTextureFunctor.h

Code/FeatureExtraction/otbDifferenceEntropyTextureFunctor.h

Code/FeatureExtraction/otbDifferenceVarianceTextureFunctor.h

Code/FeatureExtraction/otbEnergyTextureFunctor.h

Code/FeatureExtraction/otbEntropyTextureFunctor.h

...ction/otbInformationMeasureOfCorrelation1TextureFunctor.h

...ction/otbInformationMeasureOfCorrelation2TextureFunctor.h

...tureExtraction/otbInverseDifferenceMomentTextureFunctor.h

Code/FeatureExtraction/otbMeanTextureFunctor.h

Code/FeatureExtraction/otbSumAverageTextureFunctor.h

Code/FeatureExtraction/otbSumEntropyTextureFunctor.h

Code/FeatureExtraction/otbSumVarianceTextureFunctor.h

Code/FeatureExtraction/otbTextureFunctorBase.h

Code/FeatureExtraction/otbTextureImageFunction.h

Code/FeatureExtraction/otbVarianceTextureFunctor.h