[Korean] Use the SUBLANG_NEUTRAL in Korean resources.

[Mikołaj Zalewski]

  It should make no differance for Korean is you use SUBLANG_NEUTRAL or 
SUBLANG_DEFAULT as there is only one sublang.
  SUBLANG_NEUTRAL is a fallback that is used if no translation is 
available in the user's selected sublang. In can be used for locales 
that have many sublangs (e.g. French have French (France), French 
(Belgian), French (Canada), French (Swiss) etc) but the language is the 
same so it's enough to make one translation.
  While making the translations statistics I've found that 
SUBLANG_NEUTRAL and SUBLANG_DEFAULT are often randomly mixed. Maybe I 
should make a wiki page where people knowing the language could write if 
it requires separate translations for each sublang or one translation 
with SUBLANG_NEUTRAL and then update all the files?

Mikolaj Zalewski