Log Message:
mpop: Update to 1.4.17

Changes:
Version 1.4.17:
- Added a new configuration command 'eval' to replace the current configuration
  file line with the output of a command (similar to passwordeval, but more
  general).

Version 1.4.16:
- No significant changes.

Version 1.4.15:
- Added mpopd, a minimal POP3 server that delivers mails from a local mailbox
  in maildir format. It can be used by end users as a way to handle incoming
  mail via mpop with mail clients that insist on using POP3.

Version 1.4.14:
- No significant changes.

Version 1.4.13:
- Added support for SCRAM-SHA-256 authentication via GNU SASL

Version 1.4.12:
- Added support for libtls as an alternative to GnuTLS

Version 1.4.11:
- Added support for XOAUTH2, the predecessor of OAUTHBEARER.
- The passwordeval command can now handle very long input, which can be
  necessary for OAUTHBEARER and XOAUTH2.
- GnuTLS >= 3.4 is required