Refer to FontAwesome icons by their class names

[appel]

Forgive me if this has been asked and answered already, I couldn't find it in issues. It would be great for legibility if we could fetch icons by their class names, so text=fa-plus instead of text=.

They do exactly this at imgplaceholder.com:
https://imgplaceholder.com/400x400/ddd/fff/fa-plus?font-size=96

[imsky]

that's a good point, i haven't checked ligature support for icon fonts yet