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

Conflicts:
- `app/controllers/api/v1/statuses_controller.rb`:
  Conflict due to upstream adding a new parameter (with_rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/services/post_status_service.rb`:
  Conflict due to upstream adding a new parameter (rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Conflict due to us not exposing theme settings here (as we have
  a different flavour/skin menu).
  Took upstream change, while still not exposing theme settings.
- `config/webpack/shared.js`:
  Coding style fixes for a part we have rewritten.
  Discarded upstream changes.

app/controllers/application_controller.rb

@@ -30,6 +30,7 @@ class ApplicationController < ActionController::Base
   rescue_from Mastodon::NotPermittedError, with: :forbidden
   rescue_from HTTP::Error, OpenSSL::SSL::SSLError, with: :internal_server_error
   rescue_from Mastodon::RaceConditionError, with: :service_unavailable
+  rescue_from Mastodon::RateLimitExceededError, with: :too_many_requests
 
   before_action :store_current_location, except: :raise_not_found, unless: :devise_controller?
   before_action :require_functional!, if: :user_signed_in?
@@ -181,6 +182,10 @@ class ApplicationController < ActionController::Base
     respond_with_error(503)
   end
 
+  def too_many_requests
+    respond_with_error(429)
+  end
+
   def single_user_mode?
     @single_user_mode ||= Rails.configuration.x.single_user_mode && Account.where('id > 0').exists?
   end