Handle out of order task messages

[matthewrmshin]

This consolidates the remaining issue in #115 and #192.

... currently a task proxy goes into the failed state if it gets a succeeded message before a started message - whereas we should assume the succeeded message is genuine and the started message just didn't get through for some reason.

(A related issue: (@hjoliver please correct me if I am wrong...) The time of an event is currently recorded as the time when the suite receives the message. In the circumstance when a suite fails to receive the message at the correct time of the event, the recorded time of the event will be incorrect. It would be nice if the actual event time is also sent with the message in these circumstances.)

See also #350.

[hjoliver]

The time of an event is currently recorded as the time when the suite receives the message.

That's correct Matt.

[hjoliver]

Note I've moved the "related issue" above to #380.

[hjoliver]

This issue is done when #364 is merged. Currently on that feature branch:

• succeeding before all outputs completed just results in a warning and artificially completes all outputs.
  • this applies to succeeded message arriving before started too.
• receiving additional messages after succeeded just generates warnings
• the order of internal outputs doesn't matter.