Update Proterozoic and Archaean HEX codes for periods, eras and eons.

[richardstockey]

The pre-Phanerozoic colour codes were previously a series of pinks that did not correspond to the geologic timescale. I have here updated all instances I could find to match international geologic timescale standards for the Proterozoic and Archaean. HEX codes used from https://github.com/crimeacs/Geochronological_Colors/blob/master/Geochronological_scale_HEX.pdf. I have visually confirmed that this matches colours used in ICS and GSA timescale charts.

[willgearty]

Thanks for putting this together @richardstockey, making sure these colors are correct is definitely important. At the moment, I periodically pull the timescale data (using this script) from the Macrostrat API (e.g., international periods), which is usually pretty up-to-date with the ICS changes. However, it appears that they have the wrong colors in the API for lots of these older time periods as you've discovered and remedied here. This PR is great, but I'm worried that I'll just end up overriding these changes the next time I update the timescale from the Macrostrat API, so we probably want to fix this in their API first and then update deeptime's data from that. Maybe @davenquinn or @cambro could help us out or point us in the right direction?

[cambro]

We at Macrostrat use custom colors for the Neoproterozoic and Mesoproterozoic because in map-based renditions of the colors are visually very difficult to distinguish from the Paleogene. You can always access the originally defined colors with the API parameter "true_colors=true", like: https://macrostrat.org/api/defs/intervals?timescale=international%20periods&true_colors=true

[willgearty]

Ah, that would do it, thank you so much for pointing that out @cambro!

[willgearty]

@richardstockey I've updated the built-in dataframes using this new Macrostrat API option. Could you check out the github development version and let me know if that fixes the problem?
Before:

After:

[willgearty]

@richardstockey are you satisfied with my recent additions?

[willgearty]

I'm going to close this in favor of 5307477.