Automatically reinstall ports (UPDATE)

[Joshua Root]

> I just wanted to see if we could bump this reinstall method up to a more
> stable status.
> 
> I can and do confirm that under MacPorts 2.0.4, Xcode 4.3 (with persistent
> License Agreement), and +universal variant enabled…the restore ports TCL
> script, and steps provided on the Migration Info website
> https://trac.macports.org/wiki/Migration does work flawlessly.

It's pretty stable as far as it goes, yes. But it does come with some
caveats. Off the top of my head:

 * It does not handle conflicting ports gracefully at all, it just fails
when it comes across them. (You can have conflicting ports installed at
the same time, just not active.)
 * Probably an even bigger one is that it doesn't restore the
requested/unrequested status of the ports. This information isn't
actually present in the 'port -v installed' output. I think everything
ends up marked as requested.

- Josh