Family timing information.

[hjoliver]

Another user request:

Currently families show no timing information in cylc. Would it be possible to add this? T-submit & T-start would come from the first task in that family to startup; T-finish from the last to finish.
[and ...] we could see how long an entire cycle took to complete.

I'm not sure this would be very useful at whole-cycle level, but it would be good for task families.

[matthewrmshin]

Timing and other metrics can be very useful for questions such as:

• What are the total and elapsed times consumed by a cycle?
  • ... for jobs submitted to a given batch system?
• And for other resources, if they are collectable.

[hjoliver]

This isn't trivial as task families are virtual - currently we don't actually know when a family is finished at a particular cycle point, because family syntax is expanded in terms of member tasks when the suite is parsed, and hierarchy information is only retained as means grouping whichever members (at a particular cycle point) happen to be present in the task pool.

[hjoliver]

Closing as superseded by #1894