Bug report #1823487 (http://curl.haxx.se/bug/view.cgi?id=1823487) pointed

out that SFTP requests didn't use persistent connections. Neither did SCP
ones.  I gave the SSH code a good beating and now both SCP and SFTP should
use persistent connections fine. I also did a bunch for indent changes as
well as a bug fix for the "keyboard interactive" auth.