10/24/13  dhb     Pass scaling args to packing routine and truncate test image.  These were needed to make this work with my Bits++ in Color++ mode today.  I think the cropping has to do with the spatial res of my
monitor.  How this ever worked without the scaling args, though, is unclear to me.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Merge branch 'master' of https://github.com/Psychtoolbox-3/Psychtoolbox-3