xF2 Add-on Auto OpenGraph for threads 1.0.0

A simple add-on that allows to set automatically the Open Graph image of a thread using the first image (embedded or attached) of the first thread post. Useful for sharing threads on social networks (Twitter, Facebook, etc...).

This add-on uses @JoyFreak's "[JoyFreak] Set Open Graph Image" template modification. Thanks to him for his permission.