0.8.0

last minor release before 1.0.0

• switch internal actor mailbox to flume from crossbeam-channel
  • crossbeam-channel is still being used to keep actors thread independent
  • see github issue #13 for reasoning
• added generic ActorInitMessage without a generic Handler implementation
  • a Handler<ActorInitMessage> can optionally be implemented by the user for any actor which can then be used to initialize the actor
• update documentation + tests + examples