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/javascript/styles/mastodon/modal.scss

@@ -18,3 +18,9 @@
     background: url('~images/elephant_ui_plane.svg') no-repeat left bottom / contain;
   }
 }
+
+@media screen and (max-width: 600px) {
+  .account-header {
+    margin-top: 0;
+  }
+}