ordered categorical data

[piever]

Consider whether we need some specific support (for instance with a discretised batlow) for categorical variables with a well-defined order (eg, describing a price or an age, or bins of a continuous variable). It could use the categorical keyword of cgrad.

[knuesel]

This would mostly affect the colormap? And does it makes sense then to keep the isless definition on NonNumeric?

[jtrakk]

This can also affect facet order and barplot bar order.