indicate use of combM+F on comp plots

[iantaylor-NOAA]

In the setup for length and age comps there is an option to combine males and females below a given bin number to avoid fitting to any noise associated with misidentification of the sex of the smallest fish which are often hard to distinguish.

I think this is a useful option, but when it gets used, the combined observed and expected proportions are reported in the female bin, leading the r4ss figure to look something like the one below. It would be better to distinguish the bins where the obs and exp are combined, such as via a different color as well as potentially mirroring the values to the male side.

This may require additional output in Report.sso as the absence of observed and expected values could also be caused by tail compression.

This is a low priority. I'm just posting it here while I'm thinking of it.