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

Conflicts:
	README.md
	app/controllers/statuses_controller.rb
	app/lib/feed_manager.rb
	config/navigation.rb
	spec/lib/feed_manager_spec.rb

Conflicts were resolved by taking both versions for each change.
This means the two filter systems (glitch-soc's keyword mutes and tootsuite's
custom filters) are in place, which will be changed in a follow-up commit.

app/controllers/admin/settings_controller.rb

@@ -21,6 +21,7 @@ module Admin
       activity_api_enabled
       peers_api_enabled
       show_known_fediverse_at_about_page
+      preview_sensitive_media
     ).freeze
 
     BOOLEAN_SETTINGS = %w(
@@ -31,6 +32,7 @@ module Admin
       activity_api_enabled
       peers_api_enabled
       show_known_fediverse_at_about_page
+      preview_sensitive_media
     ).freeze
 
     UPLOAD_SETTINGS = %w(