First draw of the histogram equalisation working on black&white pictures and color ones

Modules/Feature/Contrast/CMakeLists.txt

Modules/Feature/Contrast/otbContrastEnhancementFilter.cxx

Modules/Feature/Contrast/otbContrastEnhancementFilter.h

Modules/Filtering/Contrast/CMakeLists.txt

...Filtering/Contrast/include/otbContrastEnhancementFilter.h

Modules/Filtering/Contrast/otb-module.cmake

Modules/Filtering/Contrast/test/CMakeLists.txt

.../Filtering/Contrast/test/otbContrastEnhancementFilter.cxx