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

Conflicts:
- `Gemfile`:
  We updated httplog in a separate commit.
  Took upstream's change which updated it further.
- `Gemfile.lock`:
  We updated httplog in a separate commit.
  Took upstream's change which updated it further.
- `app/lib/sanitize_config.rb`:
  Upstream added better unsupported link stripping,
  while we had different sanitizing configs.
  Took only upstream's link stripping code.
- `config/locales/simple_form.pl.yml`:
  Strings unused in glitch-soc had been removed from
  glitch-soc, reintroduced them even if they are not
  useful, to reduce the risk of later merge conflicts.

Gemfile.lock

@@ -284,7 +284,7 @@ GEM
     http-parser (1.2.1)
       ffi-compiler (>= 1.0, < 2.0)
     http_accept_language (2.1.1)
-    httplog (1.4.1)
+    httplog (1.4.2)
       rack (>= 1.0)
       rainbow (>= 2.0.0)
     i18n (1.8.2)
@@ -713,7 +713,7 @@ DEPENDENCIES
   http (~> 4.3)
   http_accept_language (~> 2.1)
   http_parser.rb (~> 0.6)!
-  httplog (~> 1.4.1)
+  httplog (~> 1.4.2)
   i18n-tasks (~> 0.9)
   idn-ruby
   iso-639