Merge branch 'master' into glitch-soc/master

Merge branch 'master' into glitch-soc/master

Conflicts:
- `README.md`:
  We have different README files. Discarded upstream changes.
- `app/views/layouts/admin.html.haml`:
  Conflict due to glitch-soc theming system.
  Adapted upstream changes.
- `app/views/layouts/embedded.html.haml`:
  Conflict due to glitch-soc theming system.
  Adapted upstream changes.
- `yarn.lock`:
  No real conflict, glitch-specific dependency too close to
  an updated one. Adapted upstream change.