I18n: Update translation fr (100%).

172 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
Improve auto-maximize fn to maximize windows which size is equal to the available size

Signed-off-by: Simon Steinbeiss <simon.steinbeiss@elfenbeinturm.at>
Check for stropts.h to fix BSD build.
Updates for release.
Post release tag bump.