Update fontawesome to v5 (LTS)
Summary
Font awesome 4 which was added a few months ago is great, but the next LTS has been available for a long time and has a lot more icons to chose from.
Design proposition
Migrating from one the v4 to the v5 should be mostly painless (cf https://fontawesome.com/v5/docs/web/setup/upgrade-from-v4). Not sure if there are attention points.