Update dREL evaluation method of the ATOM_TYPE category. (#451)

The list of atom types should come from the `_atom_site.type_symbol` entry.

cif_core.dic

@@ -24141,7 +24141,7 @@ save_ATOM_TYPE
     _definition.id                ATOM_TYPE
     _definition.scope             Category
     _definition.class             Loop
-    _definition.update            2021-06-29
+    _definition.update            2023-07-13
     _description.text
 ;
     The CATEGORY of data items used to describe atomic type information
@@ -24156,7 +24156,7 @@ save_ATOM_TYPE
     typelist  = List()
 
     Loop  a  as  atom_site  {
-       type = AtomType ( a.label )
+       type = a.type_symbol
        If( type not in typelist )  typelist ++= type
      }
      For type in typelist {
@@ -27894,4 +27894,6 @@ save_
        Deprecated the _atom_type_scat.versus_stol_list data item.
 
        Changed the _type.source attribute of all SU data items to 'Related'.
+
+       Updated dREL evaluation method of the ATOM_TYPE category.
 ;