0.19.0

• Added: a new overload of Reducer.pullback for working with enum-based state. It uses a case path instead of a writable key path for extracting and embedding state for a particular enum case.
• Added: a new SwitchStore view for converting stores on enum state into stores on individual enum cases (thanks @lukeredpath for sketching out the original implementation).
• Changed: Effect.timer now calls cancelInFlight: true under the hood to automatically cancel any in-flight timers with the same cancellable id (thanks @dannyhertz). If you rely on the existing behavior, which allows for timers to interleave and stack on one another, this is a breaking change and you must manually create your timers using Publishers.Timer instead before upgrading.
• Fixed: ForEachStore has been optimized and a crash related to removing rows has been fixed.
• Fixed: documentation cleanup.
• Infrastructure: modernized example/demo code, along with assorted fixes (thanks @yimajo, @filblue).