Create function in hydra_diag to do comparison plots across runs. Initially focus on Biomass & F by species, and total biomass consumed. Idea is these can be used to compare alternative runs of same model or across models.

[gavinfay]

[gavinfay]

Commit b938e70 adds hydra_comparisons() which takes multiple hydra report files and plots overlays of predicted time series.
Currently just plots predicted biomass by species.
I tried this on the test data and another run on my local machine. @sgaichas I don't have your 10 length-bin results file to hand but an easy test might be to run the function with both the 5-bin and 10-bin versions.