* Allow attribute names to be strings. Based on the

allow-arbitrary-strinsg-in-names patch by Marc Weber.

src/libexpr/parser.y

@@ -411,6 +411,8 @@ attrpath
 attr
   : ID { $$ = $1; }
   | OR_KW { $$ = "or"; }
+  | '"' STR '"'
+    { $$ = strdup(((string) ((ExprString *) $2)->s).c_str()); delete $2; }
   ;
 
 expr_list