Loop through projector pixels in makeProjectorImages
Add method to save the correspondence data of a struct light

This data isn't normally saved with the structured light object,
but saving it will hopefully make it easier to get the camera pixels
corresponding to the projector pixels when generating the output
images for the projectors.
Generate the correspondence filename in stlightmodule
Add a class to load only the correspondence data from a stlight

I also made the scene module write the correspondence data when
creating a new scene. The correspondence data is also now accom-
panied by the X and Y size of the projector image.