-fixed bug with the film, where we were adding to the wrong pixel values.
-put the readLensFile capability into the lensRealistic class as an alternate way to input data
-started work on the "auto-magnify" funcion which is a 2-pass way to automate PSF acquisition.  First render a crude PSF - then analyze that to figure out the center position, then re-render a higher-resolution, higher quality PSF.