message.scm (message-auth-reply-public-key-success): Rename.

* src/message.scm (message-auth-reply-public-key-success): Rename
  to `message-auth-reply-public-key-ok'.
* src/message-func.c
  (guile_ssh_message_auth_reply_public_key_success): Rename to
  `guile_ssh_message_auth_reply_public_key_ok'.
examples/ssshd.scm (handle-req-auth): Handle public key state.
src/message.scm (message-reply-success): New procedure.

* src/message.scm (message-reply-success): New procedure.
* examples/ssshd.scm (handle-req-auth, handle-req-channel, main):
  Use `message-reply-success'.