Added print routine to dump out what is in a photoreceptors structure.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Added PrintPhotoreceptors to the two IsomerizatoinsIn… Demos.  Added comments in these and the CIEConeFundamentalsTest about the desirability of better integrating the CIE cone fundamental code with the isomerization calculation code.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Merge branch 'master' of https://github.com/Psychtoolbox-3/Psychtoolbox-3

Signed-off-by: David Brainard <brainard@psych.upenn.edu>

Conflicts:
	Psychtoolbox/PsychDemos/IsomerizationsInEyeDemo.m
Finish off merge.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>