Make the heat map use a colour scale similar to that by Kevin Watt, as used in
Simon Mitchell's presentation, Decompression Controversies
https://www.youtube.com/watch?v=UY61E49lyos&t=2090&authuser=0
Undersaturated: cyan -> blue ->purple -> black
Supersaturated up to M value: black -> yellow -> red
Exceeding M value: red -> white
Signed-off-by: Rick Walsh <rickmwalsh@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
ddc7f3dc98