Perceptual color

[Javyre]

Hey, just did this mostly for fun but it would be useful to have the colour transforms be perceptually monotonic.

The rationale here is that the Color lib is essentially used as a colour picker for colorscheme tweaking/creating, so the improvements described here, here and here are relevant.

What I did so far:

• Port https://bottosson.github.io/posts/colorpicker/ to a new nightfox.util.oklab module
• Use oklab colour space for perceptual blending
• Use okhsv/okhsl instead of hsv/hsl for other transforms

Issues:

• This pr currently is a breaking change as the behaviour of the existing transforms have changed.
  • We can just accept this as a breaking change or Maybe we can add an opt-in field in the setup()?
    I'll leave it up to you to say how much breakage you feel comfortable with allowing and how.
• Also currently breaking as it slightly changes the output of the tranform-based colours in the foxes' palettes.
  • What I suggest here is to just use absolute colours in the palettes wherever we care about colour stability.

Let me know if this is interesting to you. I did this mostly for fun and users who are interested could totally just copy the oklab lib I ported and use it in their overrides so this is not even necessarily worth merging.

(also thanks for a great extensible plugin and codebase!)