[ptx] Enblend 1.0

[alexandre jenny]

Hi Andrew,

You made a great tool with enblend. It works great in many case ... But not
all. 
I uploaded here a result of a enblended panorama which shows a strange
mis-interpolation 
line http://www.le-geo.com/temp/emblend1.jpg
You can see that it breaks by a vertical line the luminosity of a single
picture in that panorama. 
I can provide you the inputs pictures if you need it for debug.

Alexandre Jenny