Please add filter to allow filtering of users who Maintenance Page is loaded for

Hi!

Great job on the plugin. It continually gets better and better. I do have a request. Can you please consider converting line 2268 in file /includes/functions.php from:
if (!is_user_logged_in()) {
to (as an example):

$not_logged_in = !is_user_logged_in();
if (apply_filters('mtnc_load_maintenance_page_for_this_user', $not_logged_in)) {

?

This will help a lot as it will allow us to filter whether the maintenance page should be loaded for a particular user or not based on a different set of terms rather than just on whether the user is logged in or not. It would be SUPER helpful.

Thanks!