merge: upstream fixes

 * Prevent trying to match a failing color body regex repeatedly
 * Fix QRESYNC crash after a large number of VANISHED messages
 * Improve pgp error message for translation
 * Add SENDER to default list of IMAP headers
 * Document Sender header as a default in $imap_headers
 * Deprecate TLS 1.0 and 1.1 by default
 * Enhance docs re security of SSL/TLS version vars
 * Fix compilation without deprecated OpenSSL 1.1 APIs
 * Add mutt_buffer_addstr_n()
 * Adjust version number comment in gpgme
 * Fix classic gpg date parsing in list-keys
 * Add note about the second --with-fingerprint to gpg.rc