Request: new rangescale option for symmetric colorschemes

[adrhill]

I'd be interested in a new rangescale option for get that automatically centers the rangescale around (-1, 1) .* maximum(abs, x) of some input x, such that a 0 in the input maps to 0.5 on symmetric color schemes (e.g.:vik, :bwr, :curl, :balance, :delta).

I would gladly open a PR if I had a clue how to name this option.  😄 Maybe :symmetric, :symmetricextrema, :extremasymmetric?

[cormullion]

Nice idea. ‘symmetric’ is good, ‘centered’ or ‘midpoint’ would convey something of the idea.

[adrhill]

I like :centered since the colorschemes are not actually symmetric. 👍