message: makes the .gm looks always the same
diff: @@ -666,11 +666,15 @@ namespace {
  zip_file( zf, geological_entity_file ) ;
  GEO::FileSystem::delete_file( geological_entity_file ) ;
  + index_t nb_mesh_entites = geomodel.nb_corners() + geomodel.nb_lines()
  + + geomodel.nb_surfaces() + geomodel.nb_regions() ;
  std::vector< std::string > filenames ;
  + filenames.reserve( nb_mesh_entites ) ;
  save_geomodel_mesh_entities< Corner >( geomodel, filenames ) ;
  save_geomodel_mesh_entities< Line >( geomodel, filenames ) ;
  save_geomodel_mesh_entities< Surface >( geomodel, filenames ) ;
  save_geomodel_mesh_entities< Region >( geomodel, filenames ) ;
  + std::sort( filenames.begin(), filenames.end() ) ;
  zip_files( filenames, zf ) ;
  zipClose( zf, NULL ) ;
  