Avoid exception when color cycle overflows

Created by: Zaharid

As it turns out, matplotlib's color specification is rather useless in a programmatic setting, as we need to know how many colors we have to use it properly (or use something like f'C{i%len(color_cycle)}') which sort of defeats the purpose. Instead introduce a function that cycles infinitely, but that will warn after the first cycle. Although ideally we would make it a check that fires before computation is actually done.

Closes #250 (closed).