REFAC: rewrite of otbGenerateWrappersRstDoc.py & doc improvements

...on/Cookbook/CMake/RunApplicationsRstGenerator.sh.cmake.in

Documentation/Cookbook/CMakeLists.txt

Documentation/Cookbook/Scripts/otbGenerateWrappersRstDoc.py

Documentation/Cookbook/_static/css/otb_theme.css

Documentation/Cookbook/rst/Installation.rst

Documentation/Cookbook/rst/conf.py.in

Documentation/Cookbook/rst/templates/application.rst

Documentation/Cookbook/rst/templates/parameter.rst

Documentation/Cookbook/rst/templates/parameter_choice.rst

...ntation/Cookbook/rst/templates/parameter_choice_entry.rst

Documentation/Cookbook/rst/templates/parameter_group.rst

...ions/AppClassification/app/otbFusionOfClassifications.cxx

...Applications/AppClassification/app/otbImageClassifier.cxx

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

...ations/AppClassification/app/otbTrainVectorClassifier.cxx

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

.../Applications/AppClassification/include/otbTrainBoost.hxx

...ations/AppClassification/include/otbTrainDecisionTree.hxx

...AppClassification/include/otbTrainGradientBoostedTree.hxx

...es/Applications/AppClassification/include/otbTrainKNN.hxx