[cvsnt] BUG: 2.5.01.2025: PuTTY security alert written to console

[Torsten Martinsen]

As described in 
https://sourceforge.net/tracker/index.php?func=detail&aid=1206305&group_id=48103&atid=451972,
when CVSNT connects to a server for the first time using :ssh:, it pops 
up a message box with the well-known "The server's host key is not 
cached..." question. This is all very well, but the message is also 
written to stdout/stderr, which causes TortoiseCVS to interpret it as 
part of the output from the CVS command.

Proposed fix: Only show the question in the message box, not on the console.

-Torsten