Quick sftp status indicator.

[mouring]

[..]
> > With that being said.. have fun..  BTW.. Embeded in this patch is another
> > patch I submited to clean up handling the alocation of the progress bar.  
> 
> I'd prefer to see do_upload and do_download take a callback to handle
> the progress meter. The stuff in sftp-client.[ch] should be protocol
> related only - no UI.
> 

Mostly that is pretty easy.  Only catch is dealing with how to get 'offset'
in a reasonable away unless we span global vars over multiple files.

- Ben