3.0.0

Added

• Introductory offers. SubscriptionPackage.introductoryOffer is an IntroductoryOffer: how it
  is paid (.freeTrial, .payAsYouGo, .payUpFront), one period and how many, the price, and
  whether this customer can take it (.eligible, .ineligible, .unknown). The eligibility is
  asked of the store when the offering loads, and only for packages that have an offer.
  isEligibleFreeTrial is the one question a paywall asks before writing "7 days free", and
  regularBillingDate(from:in:) is the date the regular price is first charged, counted in
  calendar units. Anything the store did not answer "eligible" is not eligible, so a customer
  who has used the trial is never promised it.
• PaywallPlanRow shows a free trial as a caption under the plan title, from the new
  PaywallLabels.freeTrial, only when the customer is eligible. The price stays the largest text.
• Choosing an offering by identifier. SubscriptionUseCase.loadOffering(id:) and
  purchase(packageId:inOffering:); PaywallView(offering:) loads and sells from that offering.
  An identifier the dashboard does not have finds nothing — the current offering is never sold in
  its place. Both calls have default implementations that answer from loadOfferings() and
  purchase(packageId:), correct for a conformance that knows a single offering, so existing
  stand-ins compile unchanged.
• PaywallHandlers.offeringIdentifier, set by PaywallContainer from its mode. Passing it to
  PaywallView keeps the fallback to the app's own paywall selling the offering the mode named.
  Until now the fallback always sold the current offering.
• SubscriptionError.purchasePending: a purchase waiting for approval (Ask to Buy). Until now it
  arrived as .purchaseFailed.
• onPending and onNothingToRestore on PaywallView, RevenueCatPaywallView,
  PaywallContainer and PaywallHandlers. With no onPending, a pending purchase goes to
  onError as .purchasePending, so it is never silent. A restore that finds nothing still does
  not call onEntitled.
• CachedEntitlement.lastKnownStatus(gracePeriod:at:) is public, so a widget or another
  extension reading the app's EntitlementCache applies the same grace rule as the app.
• PaywallLabels.japanese, and PaywallLabels.englishFreeTrial / japaneseFreeTrial for apps
  that assemble their own labels.

Changed

• BREAKING. SubscriptionError has a new case, .purchasePending. A switch over it with no
  default stops compiling. catch patterns are unaffected.
• BREAKING. New parameters, all defaulted, on SubscriptionPackage.init, PaywallLabels.init,
  PaywallHandlers.init, both PaywallView initialisers, RevenueCatPaywallView.init and
  PaywallContainer.init. Call sites keep compiling; the signatures changed.

Migrating from 2.x

• Raise the requirement to from: "3.0.0". No call site needs to change unless it switches over
  SubscriptionError exhaustively; add .purchasePending there, as an outcome, not an error.
• A pending purchase used to reach onError as .purchaseFailed; it now reaches onPending, or
  onError as .purchasePending when there is none.
• To sell the offering a PaywallContainer mode names from the app's own paywall too, pass
  offering: handlers.offeringIdentifier to PaywallView.