Fix the string rule (that was very weird).

src/lexer.mll

@@ -245,7 +245,7 @@ rule lexer = parse
                 }
 
 (* une chaine quelconque *)
-        | "\"" ['_' 'A'-'Z' 'a'-'z']  ['A'-'Z' '(' ')' '$' '/' 'a'-'z' '.' '-' '_'] * "\""
+        | "\""   ['A'-'Z' '(' ')' '$' '/' 'a'-'z' '.' '-' '_'] * "\""
             { 
                         let lxm = Lxm.make_string lexbuf in
                           TK_STRING (lxm)