ssh-agent client support for libssh

As you might know I develop csync which is a file synchronizer. To support sftp I’m using libssh. libssh is designed to be used by programmers needing a working SSH implementation by the mean of a library. I think it is nearly feature complete. I’ve cleaned up the sftp interface last year. The only thing missing was ssh-agent support. This is implemented now in the subversion trunk and will be released as libssh 0.3. I hope we can do a release soon.