pal_vsup: Variance suppressing uncertainty palette
In clauswilke/multiscales: Multivariate scales for 'ggplot2'

Returns a palette function that turns v (value) and u (uncertainty) (both between 0 and 1) into colors.

1 2	pal_vsup(values, unc_levels = 4, max_light = 0.9, max_desat = 0, pow_light = 0.8, pow_desat = 1)

`values`	Color values to be used at minimum uncertainty. Needs to be a vector of length `2^unc_levels`.
`unc_levels`	Number of discrete uncertainty levels. The number of discrete colors at each level doubles.
`max_light`	Maximum amount of lightening
`max_desat`	Maximum amount of desaturation
`pow_light`	Power exponent of lightening
`pow_desat`	Power exponent of desaturation