ENH: improve build system

CMake/Definitions.cmake

CMake/ParseArguments.cmake

CMake/WrapperMacros.cmake

CMakeLists.txt

Code/Wrappers/ApplicationLauncherQt/CMakeLists.txt

Code/Wrappers/CMakeLists.txt

Code/Wrappers/QtWidget/CMakeLists.txt

Example/Addition/CMakeLists.txt

Example/CMakeLists.txt

Example/Smoothing/CMakeLists.txt

Example/otbAddition.cxx

Example/otbSmoothing.cxx

Testing/Core/CMakeLists.txt

Testing/QtWidget/CMakeLists.txt