Add extra fields for image and links

[Sandrine-D]

It is currently impossible to add easily a class to an image, and also a class and a rel attribute to a link (important for nofollow links)

[github-actions]

In an effort to keep our issue list manageable, we are marking this issue as stale because it has been 60 days without activity. If this issue is still relevant, please let us know by posting a quick comment so that it remains open.