v0.25.0

Minor bump: geom_area()'s default stat is now stat_align(), as in
ggplot2 (an output change for areas with more than one series; see
Migration).

Added

• StatAlign (stat_align, #172). Before stacking, it interpolates every
  group of a panel onto shared x positions: every x, each group's zero
  crossings, and a tiny step either side of them. It pads each group with
  y = 0 just outside its range. A single group passes through unchanged;
  a group with one distinct x is dropped; repeated x become a vertical step.
  This follows ggplot2 4.0.3's StatAlign, checked against its
  layer_data() (tests/geom_area_stat_align.rs).

Changed

• geom_area() uses stat_align() by default (#172, ggplot2 parity).
  Stacked areas whose series are sampled at different x no longer dip where
  one series has no row. This was the known limitation of 0.24.0.
  Migration: to keep the 0.24.0 output, a plot with several series per
  panel sets .stat(StatIdentity) on the layer. A single-series area is
  unchanged.