Get rid of the ugly CMD_CHFLAG macro and use a const string (eg "dDU") in the

command entry structs and a couple of functions to check/set the flags.

cmd-new-window.c

@@ -43,7 +43,7 @@ struct cmd_new_window_data {
 const struct cmd_entry cmd_new_window_entry = {
 	"new-window", "neww",
 	"[-dk] [-n window-name] [-t target-window] [command]",
-	0, 0,
+	0, "",
 	cmd_new_window_init,
 	cmd_new_window_parse,
 	cmd_new_window_exec,