KO: Refreshes ko.po (#262) to v.2 without adding translations. (#1642)

Updates the `ko.po` with the v.2 English strings, without adding new
translations.
It will set the base to merge the professional translations later
(#1463).

To avoid disruptions on the live KO version, this will be merged into a
new branch (ko-v2), until all PRs are reviewed.