Color manipulation methods

[Be1zebub]

Features:
HWB support.
Color manipulation methods with HSV, HSL, HSB, HWB.

The main way to use this methods is to create colors for the UI.
For example, the Discord color scheme consists of the same hue and saturation, they just change lightness to create a beautiful color palette.

All you need to make pallete is background color, text color & accent color.
So addons theme config can be just 3-5 colors, instead of:

Demo:

hl2_ga8aLyIIvR.mp4

demo src: https://gist.github.com/Be1zebub/a015958b71eb8806f0ce5db3e55ed4c0

[robotboy655]

Do you think it's also worth porting HSVToColor and HSLToColor to Lua? Not sure how the performance would differ, but it would solve Facepunch/garrysmod-issues#2407

Also there are conflicts that must be resolved.

[Be1zebub]

is this legit? lua implementation 100500% faster
hsl2color is same results

https://gist.github.com/Be1zebub/e069b63ca4b96d16ed99fd77af2ae9aa

[Be1zebub]

ready 2 merge

[robotboy655]

The HSVToColor and HSLToColor replacements are not 1 to 1 with the C++ versions, sometimes generating an off by 1 difference (I think this is just floating point math discrepancies), and severely different when given invalid inputs.

The c++ code generates the same negative values with invalid inputs, but get changed to correct range via either float to int cast, or int to unsigned char cast.

I have applied some changes that gets it close, but not exactly the same. (off by 2)

[Be1zebub]

mod leads to unexpected results.
eg hsv 80, 1, 1 gives rgb 170, 0, 0 instead of rgb 170, 255, 0
255 % 255 == 0
better to use math.min/math.max in this case

it looks like c++ also uses mod, which is incorrect
eg C++ HSVToColor(80, 0, 1.1) gives 24, 24, 24
while lua HSVToColor(80, 0, 1.1) that using formulas from wikipedia gives 255, 255, 255 which corresponds to

if saturation == 0 then -- grayscale, depends only on value
    rgb = math.floor(value * 255) -- 280.5 (255 floor)
end

c++ 24 is like 280.5 % 255 which is 25.5 with weird rounding that you are noticed.

c++ HSVToColor(-1, 1, -1) results is 1, 4, 0 while should be 0, 0, 0 since value (brightness) is <= 0 - now it doesnt look like just a floating-point precision issue, more like error in c++ formula.