Right now our preferences list lists "en - English", "en-CA - Canadian English", and "en-GB - British English". However in reality the "en - English" is en-US ("American English" or "U.S. English").
We should update the preferences system and lang output to accurately reflect state:
- Special:Preferences should list en-US instead of 'en' and call it by a proper name.
- When en is used in user language lang="" should output en-US as oourut 'en' i18n is en-US.
- When the content lang is 'en' we should respect this as we don't know what locale the wiki's content actually uses, and lang="" for content should output 'en'.
- When a users' preference is set to flat 'en' the preferences list should have the 'en-US' entry as the selected entry.