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-if-shell.c

@@ -36,7 +36,7 @@ void	cmd_if_shell_free(void *);
 const struct cmd_entry cmd_if_shell_entry = {
 	"if-shell", "if",
 	"shell-command command",
-	CMD_ARG2, 0,
+	CMD_ARG2, "",
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_if_shell_exec,