[AndyB] Link check all 1.1

Checks links in all posts and reports any which return HTTP status code 404.

How to use step 1:
This add-on requires running from SSH.
Log into your terminal.
Navigate to the directory where you have XenForo installed.
Enter the following command:
php cmd.php xf-rebuild:linkcheckall

How to use step 2:
Add 'linkcheckall' to your forum URL.

Database:
This add-on will create a table called andy_link_check_all in your database.

Questions and answers:
Q: How long will it take to complete step 1?
A: On average it will take about 4 hours to process 500K posts.