It appears the system language detection doesn't work on [some versions
of?] macOS. Fixed.
Strangely, querying the Cocoa API for the system locale on a system in
US with the preferred language set to Korean produces the invalid locale
"ko-US" instead of the expected "ko-KR". This behavior of returning the
language with a invalid region qualifier for the language appears to
happen only with languages where macOS does not have regional variants
(this issue does not seem to occur with Canadian English, en-CA, for
example.) A fuzzy matching locale function has been added to handle
this issue.
