added public-key support to server mode, more docs
added public-key support to server mode (it can now verify a client signature)
and added a demo of that to the demo_server.py script (user_rsa_key). in the
process, cleaned up the API of PKey so that now it only has to know about
signing and verifying ssh2 blobs, and can be hashed and compared with other
keys (comparing & hashing only the public parts of the key). keys can also
be created from strings now too.
some more documentation and hiding private methods.
lots more documentation, and added Transport.connect()
renamed demo_host_key to demo_rsa_key. moved changelog to a separate file,
and indicated that future changelog entries should be fetched from tla.
tried to clean up "__all__" in a way that makes epydoc still work.
added lots more documentation, and renamed many methods and vars to hide
them as private non-exported API.
Transport's ModulusPack is now a static member, so it only has to be loaded
once, and can then be used by any future Transport object.
added Transport.connect(), which tries to wrap all the SSH2 negotiation and
authentication into one method. you should be able to create a Transport,
call connect(), and then create channels.