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

Conflicts:
	app/javascript/styles/mastodon-light.scss
	config/locales/en.yml
	config/locales/fr.yml
	config/locales/simple_form.pl.yml
	config/themes.yml

Conflicts resolved by deleting config/themes.yml,
marking app/javascript/styles/mastodon-light.scss as added,
and taking all new translation strings, not removing anything from
them.

app/javascript/mastodon/locales/en.json

@@ -284,6 +284,8 @@
   "tabs_bar.local_timeline": "Local",
   "tabs_bar.notifications": "Notifications",
   "tabs_bar.search": "Search",
+  "timeline.media": "Media",
+  "timeline.posts": "Toots",
   "ui.beforeunload": "Your draft will be lost if you leave Mastodon.",
   "upload_area.title": "Drag & drop to upload",
   "upload_button.label": "Add media",