Allow trails to have a fixed assigned color (to match physical markers on the path)

[christiaangoossens]

Many walking paths in the Netherlands are marked by colored bollards. Therefore, most routes have an assigned color. I would like to assign this color in Wanderer as well, to make sure that the color on the map/trail detail page matches the color you should follow on the path itself. Basic color swatches is good enough (for instance: red, yellow, green, blue).

For an example of the colors, look at: https://www.brabantslandschap.nl/ontdek-de-natuur/wandelroute-groote-heide-46-km?category=Wandelroute&omgeving=Heeze-Leende. This route is Red.