v3: GMG + p4est
metflow: the way the hierarchy of meshes is defined in order to use GMGM is not compatible with mesh p4est implementation. -> need to perform a deep copy of mesh object (incl. mesh database)
metflow: the way the hierarchy of meshes is defined in order to use GMGM is not compatible with mesh p4est implementation. -> need to perform a deep copy of mesh object (incl. mesh database)