New translation: Danish
(cherry picked from commit 0d562164c70b01852db2535aec474c5ea903e40d)
Forgot to add Danish to the LINGUAS file.
(cherry picked from commit 9dfac8e45a12223c7b1b8dee444f5ed0c1816791)
Same as in master:
* update all language PO files
* resolve issue with incorrectly declared % sign fixed yesterday
* remove plural forms from zh_CN translation (confirmed w/ Wu Tianhou)
* all files now comply with the "msgfmt -c" consistency check