0.67.0

A guard says what an absent value compares as, and an external branch can be narrowed to some rows.
2 added, 3 changed, 6 fixed.

Changed

• G4: external: may carry when_subject: to apply only to the rows it selects; set format: ess/29 to use it (#554).
• G1 grid O: a guard may write coalesce(x, d) == v for an absent Optional; set format: ess/29 to use it (#620).
• One-time read cells name the reader, in new suites ess-conformance/56/57; older suites keep their bytes (#614).
• From format: ess/29 a branch declared below one a later step answers is refused; reorder such branches (#554).
• Entity Runtime's RelatedGuardUnsupported refusal says why no bound row copy stands in; specs unchanged (#554).
• A guard's coalesce(x, d) reads d where x is absent, not Unknown; specs unchanged, regenerate suites (#620).
• A ranked head scoped by another head's value ranks above the rows its scope placed; specs unchanged (#618).
• 4 more in the changelog.

Every change: CHANGELOG.md § 0.67.0