[ptx] Hugin .5 rc2 and autopano-sift

[hugin at camner.net]

After installing the new rc2 and resetting the preferences to the
default, I get farther than before in running autopano-sift, but it
still doesn't run.  Under rc1 Hugin would crash when trying to set the
location of the autopano-sift executable.  That now works correctly, and
I can start the autopano process....a window opens, showing the call to
autopano-sift.  Then, that task quickly terminates.

The following message is reported;

Cannot open autopano_result_tempfile0.oto for reading.  This is an
indication that the call to autopano failed, or wrong command line
parameters have been used.

Hopefully this means something to someone....