Feature idea: intelligent due date colouring (#309 successor)

[tinmarino]

Issue #309 suggested to colorize dates, which have been implemented in pr #1315 (thanks @claman).

But an improvement idea from @Nudin comment:

The deluxe version of this would be having different color-highlighting depending on how close the date is – but not sure how hard that would be…

With an implementation example Here (by @ranebrown comment).

Good luck to the volunteer, I think it would be a great feature!