Small fixes in distributed graph and DistParmetisDistribution

dist_graph_0_test.vtk

dist_graph_1_test.vtk

openfpm_data

openfpm_io

src/Decomposition/CartDecomposition.hpp

src/Decomposition/CartDecomposition_unit_test.hpp

src/Decomposition/DistParMetisDistribution.hpp

src/Decomposition/ParMetisDistribution.hpp

src/Graph/CartesianGraphFactory_unit_test.hpp

src/Graph/DistCartesianGraphFactory_unit_test.hpp

src/Graph/dist_map_graph.hpp

src/Graph/dist_map_graph_unit_test.hpp

src/main.cpp

src/parmetis_dist_util.hpp

src/parmetis_util.hpp