Individual subject and meridian displacement

[gkaguirre]

Major changes:

• Can now call makeDisplacementMap with k-v pairs that identify a source RGC and cone density file
• Fixed an imperfection in the calculation of displacement that had prevented points from being displaced all the way back to cone-zero
• calcDisplacement and applyDisplacement are now stand-alone meridian functions
• the meridian validation function now shows that displaced mRGC countsPerRing matches the mRF counts per ring function for each meridian
• Fixed up the curcio average validation
• Generated some additional raw cone and RGC density files based upon the left and right eye averages of subject 29986, and an average cone density function based upon the average of exponential parameters of individual subject data.