Add support for generating material design themes

[vkottler]

Figure out what https://material.io/design/color/the-color-system.html#tools-for-picking-colors is doing (likely in HSL-space) and create interfaces to generate "themes"

We should probably make a higher level "color" that has both HSL and RGB, then we can make a set of colors from that (theme class)

[vkottler]

Drive-by upgrade - make sure both Rgb and Hsl colors can have valid == checks done on them between each of the two types so that you can check if rgb1 == rgb2 and rgb1 == hsl1

[vkottler]

Consider adding support for "alpha channel" in colors https://developer.mozilla.org/en-US/docs/Web/CSS/color_value

[vkottler]

We finished adding alpha channels to RGB and HSL, can now add a Color to a style attribute.

Should be ready to work on this issue (and figure out how we want to organize colors in general)

[vkottler]

Something we should implement: https://github.com/material-components/material-components-web/blob/master/packages/mdc-theme/_theme-color.scss#L42

[vkottler]

Google used https://gka.github.io/chroma.js/#color-darken

[vkottler]

This tool is a good example of what's going on probably: http://vis4.net/palettes/#/32|s|00429d,65ffe9,ffffe0|ffffe0,ff005e,93003a|1|1

[vkottler]

Add a class for color palette, figure out a way to plot an analysis of the palette (just show trends)

add the material design themes to the code

find the actual material design generator code

[vkottler]

This person has the "Google algorithm" https://github.com/edelstone/material-palette-generator

[vkottler]

Things to read / look at:

• https://design.tutsplus.com/articles/advanced-color-theory-what-is-color-management--cms-26307
• http://colorizer.org/
• https://www.ethangardner.com/articles/2009/03/15/a-math-based-approach-to-color-theory-using-hue-saturation-and-brightness-hsb/

[vkottler]

We need to support "HCT": https://github.com/material-foundation/material-color-utilities/blob/main/typescript/hct/hct.ts

To have a conversion to RGBA, we may need to add support for a few other color or perception models.

The Google code seems to be using: https://en.m.wikipedia.org/wiki/RGBA_color_model

[vkottler]

Not worth the effort: https://github.com/vkottler/svgen/wiki#choosing-colors