This is the first step towards reusing the same spectrum information rather than fetching it renewed each time.
One caveat with this is that you will HAVE to be sure that all workspaces in the group are equivalent in terms of instrument detector mappings etc.
What i intend to do next is:

1) For workspaces that look to relate to multiperiod group workspaces, default to reuse the spectrum-detectector mappings, once obtained on a lazy basis.
2) Put a boolean property with value in place (which defaults to true) called "PredictiveInstrumentLoading". If false, we would go back to old behaviour.

There is a naming issue here, which is actually the root cause of the problem! The query that was being performed retrieved the number of workspace entries, NOT the number of periods.
Going forward. If the number of periods exactly matches the number of workspace entries, we have a multiperiod group workspace, and can happily apply the optimisations we want.

Next step will be to actually extract the nperiods. To do that we need to try to fetch it out of the logs for The first entry.

There are lots of TODOs still to resolve. We also need to add tests for this sort of multiperiod loading.

We are not currently handling log extraction properly, which is why the test is failing.

File size is just over the threshold, but shouldn't be a problem. I've tried to trim it down as much as possible.

This fixes the regression test. We clear the logs off the temporary workspace, that way we don't have to do a similar thing in the loop, and we avoid copying them over each time. This is not a fully formed solution, but it's a start.

Also better robustness around workspace type.

Should read better now, although the entire algorithm is still a mess.

This does result in a speed up, but the caching is being bypassed at the moment since our strategy is to clone and overwrite. I've removed the caching code as part of the clean up, but I've kept the SpecInfo type around as it makes the usage clearer, and does not result in a performance penalty.

Extend tests. Do not process spectrum lists.