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

db/migrate/20180206000000_change_user_id_nonnullable.rb

@@ -1,6 +1,8 @@
 class ChangeUserIdNonnullable < ActiveRecord::Migration[5.1]
   def change
-    change_column_null :invites, :user_id, false
-    change_column_null :web_settings, :user_id, false
+    safety_assured do
+      change_column_null :invites, :user_id, false
+      change_column_null :web_settings, :user_id, false
+    end
   end
 end

db/migrate/20191031163205_change_list_account_follow_nullable.rb

@@ -1,5 +1,7 @@
 class ChangeListAccountFollowNullable < ActiveRecord::Migration[5.1]
   def change
-    change_column_null :list_accounts, :follow_id, true
+    safety_assured do
+      change_column_null :list_accounts, :follow_id, true
+    end
   end
 end