merge: upstream fixes (mutt/default)

 * Updated Ukrainian translation
 * Updated Russian translation
 * Updated German translation
 * Updated Danish translation
 * Updated Catalan translation
 * Updated Japanese translation
 * Fix the new certificate prompt translations.
 * Fix fp resource leak. (closes #3965)
 * Fix rv assignment in mutt_window_mvprintw(). (closes #3964)
 * Add warning about using inline pgp with format=flowed. (closes #3963)
 * Remove 'really' from the purge-message help description.
 * Updated French translation