avoid race conditions when workers have not updated after annotations are added

Noticed when processing a JVL file generated via launchApp from JPred Results.

I noticed a secondary structure consensus annotation appeared for the result of a jpred prediction, but the consensus was incomplete - suggesting it was created but never refreshed .. and so removed since there's only one annotation track. When I loaded the same JVL again, the 2-struc consensus row did not appear. This is almost certainly a manifestation of the worker not waiting until all annotations were added before analysing.