Add translator for Korean native encoding, cp949

It's default encoding for Korean MS Windows. *sigh*

The cp949 translator use lookup file, `cp949.dat` which is generated
from "cp848 to Unicode table";

    http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP949.TXT

with this script;

    https://gist.github.com/suapapa/5306329