Started off the day with some more improvements and bug fixes for export
remotes.

Then I noticed that there is no progress displayed for transfers to export
remotes; it seems I forgot to wire that up. That really ought to be handled
by the special remote setup code, the same way it is for non-export
remotes. But it was not possible to do it there the way that export actions
are structured.

I got sidetracked with how S3 prepares a handle to the server. That didn't
work as well as it might have; most of the time each request to the remote
actually prepared a new handle, rather than reusing a single handle. Though
the http connection to the server did get reused, that still caused a lot
of unncessary work. I fixed that, and the fix also allowed me to
restructure export actions in the way I need for progress bars.

I've ran out of time to finish adding the missing progress bars today, so
I'll do it tomorrow.

Today's work was sponsored by Jake Vosloo [on Patreon](https://patreon.com/joeyh).
