Split subtract in 2 methods ?

[lpatiny]

subtract allows an Image and a Mask but in the code there is practically nothing common depending the kind of images.

image-js-typescript/src/compare/subtract.ts

Lines 37 to 40 in 0af6d0a

	export function subtract(
	image: Image | Mask,
	otherImage: Image | Mask,
	options: SubtractImageOptions = {},

Should we not just split this method ? One for Image and one for Mask.

This could be part of the refactor:

#304

Should we in the folder operators split the one for Mask and the one for Image and have helpers if the code is common ?