v2.1.0

v2.1.0 — the report says how much of the matrix ran

Added: summary.planned on AuditRun, so a CI job reading audit.json can see
that a run covered less of the matrix than it planned. Until now only the
terminal said so, because only the CLI held the matrix.
RESULT_SCHEMA_VERSION 1.3.0 -> 1.4.0, additive.

A minor rather than a patch: SemVer calls added functionality a minor, and
shipping this as 2.0.1 would leave anyone pinned to ~2.0.0 unable ever to
receive the field.

Fixed: the 43 internal identifiers still in the tree at 2.0.0, 34 of them
in src/ and therefore in that published tarball.