Work in progress for the use of opencl with starpu

CMakeLists.txt

Src/GroupTree/FGroupTaskStarpuAlgorithm.hpp

Src/GroupTree/FStarPUOpenClWrapper.hpp

Src/GroupTree/FStarPUUtils.hpp

Src/GroupTree/OpenCl/FEmptyKernel.cl

Src/GroupTree/OpenCl/FOpenCLDeviceWrapper.hpp

Src/ScalFmmConfig.h.cmake