examples SPH update

example/Vector/0_simple/main.cpp

example/Vector/4_multiphase_celllist_verlet/main.cpp

example/Vector/7_SPH_dlb/main.cpp

openfpm_numerics

openfpm_pdata.doc

src/Decomposition/CartDecomposition.hpp

src/Decomposition/Distribution/ParMetisDistribution.hpp

src/Graph/CartesianGraphFactory.hpp

src/Graph/ids.hpp

src/Makefile.am

src/Vector/vector_dist.hpp

src/Vector/vector_dist_MP_unit_tests.hpp

src/Vector/vector_dist_comm.hpp

src/Vector/vector_dist_multiphase_functions.hpp

src/Vector/vector_dist_unit_test.hpp