Added ExtAdvS separate from AdvS in Sentence

src/english/SentenceEng.gf

@@ -56,7 +56,8 @@ concrete SentenceEng of Sentence = CatEng ** open Prelude, ResEng in {
       c2 = cl.c2
     } ;
 
-    AdvS a s = {s = a.s ++ "," ++ s.s} ;
+    AdvS a s = {s = a.s ++ s.s} ;
+    ExtAdvS a s = {s = a.s ++ "," ++ s.s} ;
 
     SSubjS a s b = {s = a.s ++ s.s ++ b.s} ;