correctly parse comment at beginning of file

src/main/jastadd/parser/RelAst.parser

 GrammarFile goal
-  = comment_list.c       {: return new EmptyDeclaration(c); :}
+  = comment_list.c grammar_file.f {: f.getDeclarationList().insertChild(new EmptyDeclaration(c), 0); return f; :}
   | grammar_file
 ;