[ptx] Release: autopano-sift 1.7, including Windows installer, no Gtk# required

[Rob Park]

Sebastian Nowozin wrote:
>   + Revamp Gtk GUI to include all options offered on the command line utility.

Oh, I forgot to mention this about the Gtk GUI. The first time I used 
it, when I saw the greyed out (disabled) "Exit" button on the progress 
window, I was a little confused. Of course, I figured it out once it was 
finished and it lit up.

What I'd like to see is during the process, instead of having a greyed 
out, disabled, useless "exit" button, you could have a "cancel" button 
that would kill autopano-sift, which would then change to "Exit" once 
it's finished.

Just a nitpick.