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

Conflicts:
	app/controllers/application_controller.rb

Changed instance theme selection by instance flavour selection.

app/views/layouts/application.html.haml

@@ -21,6 +21,9 @@
         = javascript_pack_tag "locales/#{@theme[:flavour]}/en", integrity: true, crossorigin: 'anonymous'
     = csrf_meta_tags
 
+    - if Setting.custom_css.present?
+      = stylesheet_link_tag custom_css_path, media: 'all'
+
     = yield :header_tags
 
     -#  These must come after :header_tags to ensure our initial state has been defined.