Release v2.1.0

Added

• CommandDefinition now carries the command's authorize requirement, its require rules and its reads declarations (#23).
• Command authorization is carried as a requirement tree — PolicyReference and LogicalRequirement — so A or B and C stays distinguishable from (A or B) and C. AuthorizationRequirement.Policies() gives the flat set of names to a consumer that only needs those (#23).
• ProducedEvent now carries the event source a produces … for clause names (#23).
• EventDefinition now carries the tags declared on the event (#23).
• Specification now carries given readmodel and then readmodel steps, which the existing SpecificationRunStepKind.ThenReadModel had nothing to feed it (#23).
• A concept's @pii and @sensitive attributes, and the reason each was declared for, now travel on the schema of every property typed as that concept. They were dropped entirely on import, leaving personal data indistinguishable from any other value (#23).

Fixed

• A binary break in a published contract now fails the build instead of surfacing as a missing-method fault in a consumer at run time.