Changes

[https://doi.org/10.1109/MCG.2007.46 Rainbow colormap still harmful]

[https://doi.org/10.1109/MCG.2007.46 Rainbow colormap still harmful]

[http://colorbrewer2.org/ A webtool for testing colormaps]

[https://colorbrewer2.org/ A webtool for testing colormaps]

[http://en.wikipedia.org/wiki/HSL_and_HSV HSL and HSV] entry in Wikipedia

[https://en.wikipedia.org/wiki/HSL_and_HSV HSL and HSV] entry in Wikipedia

[http://www.vendian.org/mncharity/dir3/blackbody/ What color is a blackbody?] (for constructing the "heat" color map.)

[http://www.vendian.org/mncharity/dir3/blackbody/ What color is a blackbody?] (for constructing the "heat" color map.)