I18n: Update translation ast (87%).

189 translated messages, 27 untranslated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
Don't free a passed in pointer

xfce_backdrop_image_data_release tries to null a pointer given
as argument after free. This patch fixes it by freeing the data
in the calling functions.
I18n: Update translation pl (100%).

216 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
Revert "g_file_trash_async is too new (Bug 10786)"

This reverts commit f88ce1c815455bb207d3ac608bb8e7bcedfbcc89.
Revert "Use GIO directly for delete/trash operations (Bug 10778)"

This reverts commit d48b40f6623a758ff128f5b22b2bd3e581b5b2a3.

This doesn't fix the issue for everyone and removes the confirmation
dialog. Reverting this brings the confirm dialog back (Bug 10857).