Color wheel v1

A first attempt to distribute colors as close to a square color wheel as possible.

General algorithm: for each band/square of untouched pixels expanding out from the center, choose pixels to place in that square based on the following:

• Brightest colors get priority
• Least-represented hues get priority within a brightness
• Most-saturated colors get priority within a hue
• Order the hues ascending from 0-6 (magenta = 0, red = 1, green = 3, etc.)
• Insert monochrome colors where applicable, trying to minimizes how far it shifts each hue away from its "ideal" location (magenta at top, red 60 degrees left, green at bottom, etc.)
• Place hues next to each other in order around that band of pixels

There's a clear point when it changes from one hue set to another, so I'll have to try again prioritizing an even distribution of hues