merge: upstream fixes (mutt/default)

merge: upstream fixes (mutt/default)

 * Fix improper signed int conversion of IMAP uid and msn values.
 * Change imap literal counts to parse and store unsigned ints.
 * Fix imap status count range check.
 * cmd_handle_fatal: make error message a bit more descriptive
 * Updated French translation.
 * Create pgp and s/mime default and sign_as key vars. (see #3983)
 * Add missing setup calls when resuming encrypted drafts.
 * mutt_pretty_size: show real number for small files
 * examine_directory: set directory/symlink size to zero
 * Update pl.po
 * Fixed GPGME translations that weren’t shown but affected the keyboard
 * docs: update encrypt-to-self
 * Update smime.rc: Typo fix, consistent headings
 * Add pgp_default_key and smime_sign_as info to contrib rc files.
 * Split Copyright and Thanks in help output.
 * strip out copyright translations