[css-color-4][css-color-5] Consistently spell as "color space"

[tabatkins]

The Color specs inconsistently spell the term as "colorspace" and "color space". Color 4 currently prefers "colorspace" (5x as many usages), but Google Trends suggests the internet in general slightly prefers "color space".

This impacts APIs - in whatwg/html#6562 (comment) the 1-vs-2 word spelling is discussed so it's clear whether the camelCase spelling should be "colorspace" or "colorSpace". There's already a web api using "colorSpace", so the thread is settling on that.

We should be consistent and spell it "color space" across the Color specs as well. Even if there's some good reason to use "colorspace", keeping things consistent across the web APIs is important.

[tabatkins]

(Raising this as an issue just so @svgeesus can object if necessary; otherwise I'll happily make the edits.)

[svgeesus]

I'm less interested in what people use informally on the Web and more interested in the correct technical term. Checking the indexes and glossaries of five books on color theory, color management, color appearance modelling and gamut mapping shows that all have color space

So, +1 to that.