Expand command-line specifiers (e.g. %a) in command-lines passed to ;EXEC

... and friends

For Gamgee

exec/str_cmds.js

@@ -892,7 +892,7 @@ function get_nodenum(str)
 
 function get_cmdline(str)
 {
-	return get_arg(str, "Command-line");
+	return bbs.cmdstr(get_arg(str, "Command-line"));
 }
 
 function get_filename(str)