LensDistortOp bug and compatibility with negative formats.
Fixed a bug in the LensDistortOp where it has been applying the distortion upside down. Until now it has been unnoticable as the only lens model in Cortex is symmetrical in the Y axis.
Added support to the LensDistortOp for images with offset display window.
Added a test case for the LensDistort node in nuke.
The test case generates a set of test images and compares the output of the LensDistort node to that of the LensDistortOp.
Merge pull request #172 from goddardl/LensDistortOp

LensDistortOp bug and compatibility with negative formats.