Updates for release.
Post release tag bump.
I18n: Update translation ja (100%).

220 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation it (100%).

220 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation pl (100%).

220 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).