[Smart Crawl] Smart Crawl issue with shortcodes and footers

Smart Crawl 2.2.2.7 duplicates footer hooks - when created via a shortcode at least.

The free version 2.2..2.5 does n't do this.

It is easily tested with a mini plugin e.g.

```<?php
/**
* Plugin Name: Test
* Plugin URI: http://
* Description: Test
* Author: Alan
* Version: 1.0
*
*/
if ( ! defined( 'WPINC' ) ) {
die;
}
add_shortcode( 'test', 'testsc' );
function testsc($atts){
$output = "<BR>DEBUG - TEST<BR>";
add_action( 'wp_footer', function () use ( $output ) {
echo '<br>FOOTER<br>'.$output;
}, 100008 );
return $output;
}
```

With Smart Crawl 2.2.2.7 active two footer actions are added, with deactivated it works as just one.