Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `Gemfile.lock`:
  No real conflict, glitch-soc-only dependency (redcarpet) too close to an
  upstream one (rdf-normalize)
- `README.md`:
  we have different READMEs, discarded upstream's changes
- `app/views/admin/custom_emojis/index.html.haml`:
  No real conflict, different context because of glitch-soc theming
- `lib/mastodon/statuses_cli.rb`:
  Upstream added code to keep bookmarked statuses, we were already doing so
  with slightly different code. Discarded upstream's changes.
- `package.json`:
  No real conflict, glitch-soc-only dependency (favico.js) too close to
  an upstream one

app/views/layouts/admin.html.haml

@@ -21,9 +21,9 @@
         .content-heading
           %h2= yield :page_title
 
-          - if :page_heading_actions
+          - if :heading_actions
             .content-heading-actions
-              = yield :page_heading_actions
+              = yield :heading_actions
 
         = render 'application/flashes'