[MERGE] Support for Putty SSH implementation

[John Arbash Meinel]

Harald Meland wrote:
> [Alexander Belchenko]
> 
>> Dmitry Vasiliev пишет:
>>> The attached patch adds support for Putty's plink SSH implementation.
>>> Also slightly refactored SSH negotiation code and added some tests.
>> What's improvements of using plink instead of paramiko?
> 
> I would guess that Pageant (putty's "ssh-agent" equivalent)
> integration to be easier achievable (if not already present) when
> using plink than with paramiko.

Paramiko already supports pageant (as of 1.5.2?). And you need paramiko
for sftp support anyway.

Still, I think it would be nice to support plink directly. Especially
since it will make it easier to support other ssh and sftp implementations.

By the way, does this support 'bzr+ssh' using plink?

John
=:->