Enable reverse colorpalettes

[PatrikHlobil]

One sensible improvement to the current pack would be the option to reverse the color palette. Unfortunately most palettes give a darker tone (higher presence) to darker colors.

See below how to reverse the palette upon import:

https://automating-gis-processes.github.io/2017/lessons/L5/advanced-bokeh.html

Look for this command:

palette.reverse()