Added VSUP scales and guides for value-suppressing uncertainty palettes.
Added regular glyph shapes for geom_sf_glyph(),
including circle, square, triangle, hexagon.
Added Chernoff face glyphs for glyph maps.
Added geom_sf_dualmap() for combining a
colour-filled choropleth layer with a centroid-based glyph
layer.
scale_bivariate() now supports user-specified
breaks, limits, labels, and
transformations.
scale_bivariate() now supports unequal numbers of
groups across the two mapped variables.
Pixel maps now support different pixel shapes.