Add operators for types

[fnky]

It should be possible to compare types in Chroma. Such as ColorTint e.g.

var a: ColorTint = ColorTint(...)
var b: ColorTint = ColorTint(...)

Perhaps be able to merge as well

Addition

Add component a.startColor to b.startColor, and (if not nil) a.endColor to b.endColor.

var c: ColorTint = a + b

Subtraction

Subtract component a.startColor from b.startColor, and (if not nil) a.endColor from b.endColor.

var c: ColorTint = a - b

Compare

Compare hash values between component a and b. If they're equal return true, otherwise false.

var isEqual: Bool = a == b
var notEqual: Bool = a != b