[ptx] auto rotate

[Thomas Steiner]

a feature request:
please read in the exif the image rotation and adjust pictures that way in
the preview as well. I am talking about the control points tab and the
panorama preview. It's a lot easier, especially when in a panorama there are
pictures in protrait AND landscape in one panorama. And the preview should
be (automatically) so that the horizon is from the left to the right and not
bottom up... do you understand what I mean?

and a minor thing: while optmizing or finding ctrl.pts. it's impossible to
close the preview-window. Why?
Thanks,
Thomas