This function drives the [OC Marilyn Diptych color selection algorithm](https://etherscan.io/address/0x49ef13182e7a58f39a8682e1fb46b231660f8f78#code#F1#L263).
colorsVisiblyDifferent determines when two colors are "different enough" to be shown next to each other, for example one as the background and the other as Marilyn's hair.
Because OC Marilyn Diptychs are restricted to punk colors, the challenge is to require sufficient difference for the image to look good while not demanding so much that no colors will satisfy.
Looking at it again, this function seems to have a bug in that you can't determine hue difference by normal subtraction because it's a 360 degree "wheel."
This makes hue 1 degree and hue 360 degree quite close to each other, even though the absolute difference between 1 and 360 is a lot.
I'm surprised this error didn't cause more problems, actually!
