Release v1.3.0

Box Office now has a catalog: the offers an operator such as Direct sells, their prices, and the pricing arithmetic, published to products through the existing OfferPublished and OfferWithdrawn contracts.

Added

• Cratis.Showrunner.BoxOffice.Catalog NuGet package with three kinds of offer: seat plans (seats or unlimited, included modules and allowances, sales contact), modules (flat per organization or per seat, trial length, paid or preview) and compute packs (meter, quantity per period, stackable). (#50)
• Commands DefineSeatPlan, DefineModuleOffer, DefineComputePack, PriceOffer, IncludeModuleInOffer, IncludeAllowanceInOffer and RetireOffer, and the Offer read model with observable AllOffers and OffersOnSale queries. Repeating a price, module or allowance an offer already has records nothing.
• Pricing.TotalFor, PeriodEnd and Prorate, moved from Direct's Admin catalog and expressed in minor units, for monthly and yearly billing.
• SeatPlanOffers.From turns an existing seat SKU and its price into the events of an identical seat plan offer.
• OfferPublisher reactor that appends OfferPublished to the outbox when what an offer tells a product changes, and OfferWithdrawn when a published offer is retired. An unlimited seat plan publishes int.MaxValue seats, and allowances are not published because the contract has no field for them.
• Documentation for the catalog at https://github.com/Cratis/Showrunner/blob/main/Documentation/BoxOffice/catalog.md.