Merge branch 'patches/bug4594' into devel
FTP: Extended AUTH TLS config option.
FTP: Fixed SSL data connection.
FTP: Fixed typo in PBSZ error message.
FTP: Support ending the TLS control connection with REIN.
FTP: Added configuration flag to require AUTH TLS.
FTP: Support AUTH TLS (RFC 4217).
FTP: The ftp server is always the server side of TLS.
FTP: Splitted send() into low_send() and send().
FTP: Prepare for supporting AUTH TLS (RFC 4217).
Protocols: Added StartTLSProtocol.