Merge remote-tracking branch 'origin/master' into merge-upstream

Conflicts:
 	config/locales/pl.yml

The conflict in config/locales/pl.yml concerns the themes key, which is
not used in glitchsoc.  Resolution: remove the themes key-related
changes, i.e. accept-ours.

app/javascript/mastodon/locales/pl.json

@@ -284,8 +284,8 @@
   "tabs_bar.local_timeline": "Lokalne",
   "tabs_bar.notifications": "Powiadomienia",
   "tabs_bar.search": "Szukaj",
-  "timeline.media": "Media",
-  "timeline.posts": "Toots",
+  "timeline.media": "Zawartość multimedialna",
+  "timeline.posts": "Wpisy",
   "ui.beforeunload": "Utracisz tworzony wpis, jeżeli opuścisz Mastodona.",
   "upload_area.title": "Przeciągnij i upuść aby wysłać",
   "upload_button.label": "Dodaj zawartość multimedialną",