Added Brazilian Portuguese translation files.
Renamed Chinese translation folder.

Made it explicit that it's "Chinese Chinese", and not Taiwanese Chinese.
Tweaked translation handling.

Now POSIX codes are used throughout, it makes more sense and I should
have done this sooner. The masterlists will need updating to use the new
codes.
Added code support for Brazilian Portuguese.

Also fixed language selection broken in last commit, and updated archive
and install scripts.
Updated readmes.