Ref T7152. Ref T1139. This updates Phabricator so third-party libraries can translate their own stuff. Also:
- Hide "All Caps" when not in development mode, since some users have found this a little confusing.
- With other changes, adds a "Raw Strings" mode (development mode only).
- Add an example silly translation to make sure the serious business flag works.
- Add a basic British English translation.
- Simplify handling of translation overrides.