Add GPU pyfaust.Faust wrappers for concatenate, vstack, hstack, clone.

src/faust_linear_operator/GPU2/faust_TransformHelper_gpu.h

src/faust_linear_operator/GPU2/faust_TransformHelper_gpu.hpp

src/faust_linear_operator/GPU2/faust_Transform_gpu.h

wrapper/python/pyfaust.py

wrapper/python/src/FaustCoreCpp.h

wrapper/python/src/FaustCoreCpp.hpp

wrapper/python/src/FaustCoreCppGPU.hpp

wrapper/python/src/FaustCoreCy.pxd

wrapper/python/src/FaustCoreCyGPU.pxd

wrapper/python/src/_FaustCorePy.pyx

wrapper/python/src/_FaustCorePyGPU.pyx