v2.1.0

2.1.0

Pivot tables, a mark on a cell whose value just moved, and the group a reader
is inside kept under the header. Everything here is opt-in: register the
feature or leave it out.

One type-level break, in a minor on purpose: DataGridLabels gains required
members, so an application that builds its own complete table and hands it to
mergeLabels as the base no longer compiles. Nothing at run time changes.
MIGRATING.md
has the two lines that fix it.

Added

• pivot(): one field down the page by another across it, with the columns
  read from the data and every total measured from the rows
• Seven readings of a measure, a column axis you can order or trim, and the
  measures stacked on either axis
• Grid.PivotPanel to build a crossing at run time, and the whole crossing in
  a saved view
• A crossing on rowModel: 'server', carried as a normalized request
• flashCells(): a cell says when its value changed, fading over its own
  clock, restyled through a slot, two custom properties or an appearance hook
• stickyGroups: the group rows a reader is inside pinned under the header
• headerHeight and groupHeaderHeight, counted per tier
• GridFeature.columns, the extension point a crossing needed, so a feature
  can add columns an application never declared
• A formatting rule can name a pivot measure instead of a column id

Fixed

Eighteen, among them a pinned cell going transparent on a grand total row, a
server grid keeping the answer to the crossing before, and a saved view that
could turn a feature on but never off.

Every change, and why, is in
CHANGELOG.md.