cumulative update for the f13 branch
- do not send QUIT to a dead FTP control connection (#650255)
- prevent FTP client from hanging on unrecognized ABOR response
(#649347)
- return more appropriate error code in case FTP server session idle
timeout has exceeded (#650255)
- prevent FTP server from hanging on closed data connection (#643656)
- proxy tunnel support for LDAP requests (#655134)