Before, the ignore info were stored in a different file which was a bit cumbersome
for new comers. Now, this info is stored directly in the translation file as a
comment.
Before, there was no way of telling translators that a previously translated string
was in need of a new translation. Now, the dirty information is there to convey that
info.
Translations had quite a lot of cleaning in late:
* Removed some unused keys
* Added some ignores
* Applied a `cli/manipulate.translation.php -a format`