Switch color comparison space

[SimonDMC]

Using the RGB space for color comparison is pretty inaccurate due to how we perceive colors, and it can also result in weird block pallette duplications:

This pull request fixes that, using the L*a*b* color space for a more perceptually uniform color transition :)

For more information about comparing colors, check out this useful post I used to find this out :D

The actual code I ended up using comes courtesy of @ryancat who wrote the exact script needed for this