Before refactor communication of vector dist

CHANGELOG.md

example/Vector/3_molecular_dynamic/main.cpp

example/Vector/3_molecular_dynamic/main_expr.cpp

openfpm_vcluster

src/Grid/grid_dist_id.hpp

src/Grid/grid_dist_id_iterator_dec.hpp

src/Grid/grid_dist_util.hpp

src/Vector/vector_dist.hpp

src/Vector/vector_dist_unit_test.hpp