use better colors for disassembler

[lievenhey]

the current implementation of the color generation does not respect contrast, which can lead to highly suboptimal results.

I would propose the following: from stackoverflow implement this lookup table if there are less then 22 colors

if we need more, we should try to split the hsv color space in like 3 saturations and then try to jump in the saturation. (Currently we are only changing the saturation)

[milianw]

I'm fine with this, but please make sure that it looks good with dark color schemes too