Apply --no-wrap for Korean translation

Use `--no-wrap` for Korean translation to avoid unnecessary diffs.

When updating ko.po,
`msgmerge --no-wrap --update po/ko.po po/messages.pot`

Poedit's settings:
- uncheck "line-wrapping"
- uncheck "keep old formatting"

Note that with these settings/options `msgstr` will be still
line-wrapped at `\n`.