6.0

[rodydavis]

• Remove SignalStream controller
• Upgrade SignalsProvider/ComputedProvider/ReadonlySignalProvider to default imports
• Add FlutterSignal to extends ValueNotifier
• Add FlutterComputed/FlutterReadonlySignal to extends ValueListenable
• Removing deprecated methods
• Add more methods to SignalsMixin
• Switching to preact_signals package for core implementation
• Removing old deprecated methods
• Add new mixins: EventSinkSignalMixin, SinkSignalMixin, StreamSignalMixin, SetSignalMixin, ListSignalMixin, MapSignalMixin, QueueSignalMixin, ChangeStackSignalMixin, IterableSignalMixin
• Update AsyncSignal to implement EventSink
• Removing previous/initial value from Signal and Computed in favor of TrackedSignal, TrackedSignalMixin and trackedSignal()
• Update SignalsObserver to include value for signal created (instead of peek())
• Updated examples
• Remove callback to signal
• Remove toSignal extension method (causing unintended casts) in favor of .$ for Object/Object?
• Add WatchBuilder to include a child callback for caching a widget between rebuilds
• Removing ComputedProvider/ReadonlySignalProvider