Allow semicolon after discipline/nature identifier

Version 2.3.0 of the Verilog-AMS Language Reference Manual introduced
an optional semicolon after a nature and discipline identifier in a
nature and discipline declaration, respectively; e.g.,

    nature identifier;
        ...
    endnature

and

    discipline identifier;
        ...
    enddiscipline

are now also legal syntax.

ADMS behaves the same as when the semicolon is absent.

This brings ADMS one step closer to being able to parse the most
recent Accellera standard disciplines header files.

This commit fixes GitHub issue #39.

admsXml/verilogaYacc.y.in

@@ -140,6 +140,7 @@ R_s.admsParse
         ;
 R_discipline_member
         | tk_discipline R_discipline_name R_l.discipline_assignment tk_enddiscipline
+        | tk_discipline R_discipline_name ';' R_l.discipline_assignment tk_enddiscipline
           _ adms_admsmain_list_discipline_prepend_once_or_abort(root(),gDiscipline);
           _ gDiscipline=NULL;
         ;
@@ -175,6 +176,7 @@ R_discipline.naturename
 
 R_nature_member
         | tk_nature tk_ident R_l.nature_assignment tk_endnature
+        | tk_nature tk_ident ';' R_l.nature_assignment tk_endnature
           _ p_nature mynature=NULL;
           _ if(gNatureAccess) 
           _   mynature=adms_admsmain_list_nature_prepend_by_id_once_or_abort(root(),gNatureAccess);