[Dovecot] dsync verbosity, summary of transfer

[Alan McGinlay - SICS]

Hi!

I am playing with dsync and trying to fix an issue I have mentioned in 
another thread (subject: "Re: [Dovecot] Dsync error: Couldn't drop 
privileges: getgrnam") and feel that dsync could use some additional 
informational output. It would be particularly helpful while 
experimenting with a migration if it could output a transfer summary and 
/ or log separately.

A summary could be similar to that which imapsync outputs after 
completion, for example:

++++ Statistics
Transfer started on               : Thu Dec  5 20:30:05 2013
Transfer ended on                 : Thu Dec  5 20:32:00 2013
Transfer time                     : 114.3 sec
Messages transferred              : 7
Messages skipped                  : 766
Messages found duplicate on host1 : 0
Messages found duplicate on host2 : 0
Messages void (noheader) on host1 : 0
Messages void (noheader) on host2 : 0
Messages deleted on host1         : 0
Messages deleted on host2         : 9
Total bytes transferred           : 71820 (70.137 KiB)
Total bytes duplicate host1       : 0 (0.000 KiB)
Total bytes duplicate host2       : 0 (0.000 KiB)
Total bytes skipped               : 10070561 (9.604 MiB)
Total bytes error                 : 0 (0.000 KiB)
Message rate                      : 0.1 messages/s
Average bandwidth rate            : 0.6 KiB/s
Reconnections to host1            : 0
Reconnections to host2            : 0
Memory consumption                : 90.5 MiB
Biggest message                   : 39274 bytes
Detected 0 errors