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

Conflicts:
- README.md
- app/helpers/statuses_helper.rb
  Upstream moved account helpers to their own file, we had extra
  helpers there, moved too.
- app/lib/sanitize_config.rb
- app/models/user.rb
- app/serializers/initial_state_serializer.rb
- config/locales/simple_form.en.yml
- spec/lib/sanitize_config_spec.rb

app/lib/formatter.rb

@@ -337,7 +337,7 @@ class Formatter
 
   def link_to_url(entity, options = {})
     url        = Addressable::URI.parse(entity[:url])
-    html_attrs = { target: '_blank', rel: 'nofollow noopener' }
+    html_attrs = { target: '_blank', rel: 'nofollow noopener noreferrer' }
 
     html_attrs[:rel] = "me #{html_attrs[:rel]}" if options[:me]