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/statuses_controller.rb

@@ -48,7 +48,12 @@ class StatusesController < ApplicationController
 
   def embed
     use_pack 'embed'
+    raise ActiveRecord::RecordNotFound if @status.hidden?
+
+    skip_session!
+    expires_in 180, public: true
     response.headers['X-Frame-Options'] = 'ALLOWALL'
+
     render 'stream_entries/embed', layout: 'embedded'
   end