Adding funcionalities + speed up some others

example/Vector/7_SPH_dlb_gpu/main.cu

example/Vector/7_SPH_dlb_gpu_opt/main.cu

openfpm_data

src/Vector/cuda/vector_dist_cuda_funcs.cuh

src/Vector/cuda/vector_dist_gpu_unit_tests.cu

src/Vector/vector_dist.hpp

src/Vector/vector_dist_kernel.hpp