r.max & r.achieved for all spaces?

[thomased]

Two related points:

1. No in-principle reason these shouldn't be calculated for all spaces, instead of just tcspace right?

2. Another way to consider calculating both r.max and r.achieved is relative to the achievable maximum defined by the monochromatic locus for a given hue (rather than the full dimensions of a space). So that'd entail working with maxgamut etc, which I know is a bit tricky. But it's something I've seen done, e.g. in Lunau's work, and would be neat to consider.