experimental new GUI setup

[DJ Delorie]

> Ok, then I think it should be marked as optional.

I'll see what I can do about squeezing that in.

> I thought about having it return automatically to the mirrors list
> but I thought that some people might want to be able to give up at
> that point.

If they wanted to do that, they could just hit "cancel" at the mirror
list dialog.

> Yeah but I'm still concerned about the user being confused if he
> accesses an out-of-date mirror.

No worse that what we have already.  If the user switches to a *more*
out of date mirror, setup detects that and issues a warning.