Add a PlainColorObject type for functions that return color objects

[lloydk]

The ColorObject type has optional properties and doesn't accurately reflect the color object type returned by functions such as getColor() which ensures that the object returned has space, coords and alpha properties that are not undefined.

A new interface called PlainColorObject has been introduced to represent fully formed color objects.

The Color class implements the PlainColorObject interface so the Color class was removed from list of types in the ColorTypes type.

This PR also fixes the return type for functions in the interpolation module that were returning the incorrect type.

[LeaVerou]

Hey, thanks for the contribution! I've requested review from some more TS-savvy folks than me. Meanwhile, you could rebase this PR, as it now shows changes from your other, merged, PR.

[lloydk]

I managed to remove the extra commit from my original pull request but I think I ended up creating a different mess. I have no idea what I'm doing when it comes to git commands. For now I'll just wait for the review and if everything is ok we can figure out what to do next.

[jgerigmeyer]

I like this! I think there may be a few more places where we can replace ColorObject with PlainColorObject (e.g. Display.color in display.d.ts). I haven't looked through all of them, but I expect there might be other places too?

[lloydk]

I like this! I think there may be a few more places where we can replace ColorObject with PlainColorObject (e.g. Display.color in display.d.ts). I haven't looked through all of them, but I expect there might be other places too?

I tried to find all of the functions that could be switched but it's quite possible I missed a few.

The display function calls serialize which calls getColor so in the case of the display function ColorTypes is the correct type for the color parameter.

[jgerigmeyer]

The display function calls serialize which calls getColor so in the case of the display function ColorTypes is the correct type for the color parameter.

I meant the return value Display. Shouldn't it be defined as export type Display = string & { color: PlainColorObject };?

[lloydk]

The display function calls serialize which calls getColor so in the case of the display function ColorTypes is the correct type for the color parameter.

I meant the return value Display. Shouldn't it be defined as export type Display = string & { color: PlainColorObject };?

The display function calls serialize which calls getColor so in the case of the display function ColorTypes is the correct type for the color parameter.

I meant the return value Display. Shouldn't it be defined as export type Display = string & { color: PlainColorObject };?

Sorry, misread your comment. You're correct and I've made the appropriate change to the Display type.

[LeaVerou]

Just realized this PR had not been merged because it was referenced by another issue. Sorry @lloydk! FWIW @jgerigmeyer @MysteryBlokHed if I tag you for review, I fully trust you to merge the PR when/if ready. 😊