Major actor updates plus several bug fixes and minor refactoring. Please see the changelog for details.

• C native CAtomicBoolean
• C native CAtomicFixnum
• Refactored intermittently failing tests
• Added dataflow! and dataflow_with! methods to match Future#value! method
• Better handling of timeout in Agent
• Actor Improvements
  • Fine-grained implementation using chain of behaviors. Each behavior is responsible for single aspect like: Termination, Pausing, Linking, Supervising, etc. Users can create custom Actors easily based on their needs.
  • Supervision was added. RestartingContext will pause on error waiting on its supervisor to decide what to do next ( options are :terminate!, :resume!, :reset!, :restart!). Supervising behavior also supports strategies :one_for_one and :one_for_all.
  • Linking was added to be able to monitor actor's events like: :terminated, :paused, :restarted, etc.
  • Dead letter routing added. Rejected envelopes are collected in a configurable actor (default: Concurrent::Actor.root.ask!(:dead_letter_routing))
  • Old Actor class removed and replaced by new implementation previously called Actress. Actress was kept as an alias for Actor to keep compatibility.
  • Utils::Broadcast actor which allows Publish–subscribe pattern.