finish rolling back multiple maps feature

src/label_map.h

@@ -23,7 +23,6 @@ namespace LAMMPS_NS {
 class LabelMap : protected Pointers {
  public:
    int natomtypes,nbondtypes,nangletypes,ndihedraltypes,nimpropertypes;
-   std::string id;
    std::vector<std::string> typelabel,btypelabel,atypelabel;
    std::vector<std::string> dtypelabel,itypelabel;
    std::unordered_map<std::string, int> typelabel_map;