Feature request: optionally cap the max pixel count instead of max dimensions

[subtleGradient]

Use case: we have a bunch of super tall and skinny images.
Since they're so tall, they're hitting the originalSteps maximum height limit.
But since they're so skinny, they shouldn't be unnecessarily scaled down.

So, I propose calculating a maximum pixel count instead of maximum dimensions.

[subtleGradient]

I'm planning to implement this myself (if I can figure out how ;)

[subtleGradient]

node-image-steam/lib/router/router-defaults.js

Line 10 in fb47cc7

resize: { width: '2560', height: '2560', max: 'true', canGrow: 'false' },

node-image-steam/lib/processor/processor-defaults.js

Line 2 in fb47cc7

maxSize: { width: 2560, height: 2560 }

node-image-steam/lib/processor/steps/resize.js

Lines 27 to 35 in fb47cc7

	if (context.options.maxSize) {
	// request should never exceed permitted output size
	if (stepInfo.width > context.options.maxSize.width) {
	stepInfo.width = context.options.maxSize.width;
	}
	if (stepInfo.height > context.options.maxSize.height) {
	stepInfo.height = context.options.maxSize.height;
	}
	}