Catch Plot when input catch is in numbers

[chantelwetzel-noaa]

The catch figure which shows the input vs. the model estimated removed catches currently is pulling the biomass quantities regardless if the input catch was in numbers. Need to create a check for catch units and then pull and compare the appropriate columns from the CATCH data frame in the Report file.

[iantaylor-NOAA]

Thanks @chantelwetzel-noaa for reporting this.

This figure created by SSplotCatch was developed before SS_output returned the $catch table which would make comparison of observed and expected easier for models like this one where the units differ among fleets.

The whole function SSplotCatch could be revised to use $catch which would probably make the code cleaner, but would take some work. The ideas in issue #193 could be folded into this too. I've already been working on adding a plot of landings + dead discards which is currently missing, so can try to chip away at these other things as well.

[iantaylor-NOAA]

An additional refinement for the catch plots would be to create both the catch-in-biomass plots and catch-in-numbers plots when some of the fleets have catch in numbers, where right now the default is to plot catch in biomass if any fleet has catch in biomass. Commits f055fc9 and 52ab135 clean up the code and messages related to these default assumptions, but don't yet add this proposed step of plotting things both ways.