added catch by fleet diagnostics

[jcaracappa1]

• magnitude of catch
• center of gravity of catch

[andybeet]

@jcaracappa1 At first glance we are using different argument names and output names for the same things across functions. eg. fgs (used in other diagnostics function) vs fgs.file (in this new function) vs groups.file (output of get_atl_parmamfiles). Same thing with fishery/catch files. Not something i am suggesting we should fix now but might be worth doing/addressing in the future

EDIT: the explanation of some of the arguments look like they are left over from another function

[jcaracappa1]

Which argument names look unchanged?

[jcaracappa1]

@andybeet Do you think we should rename anything before merging?

[jcaracappa1]

@andybeet That should be fixed now

[andybeet]

i dont think this will run. still left over names in code. But i dont have a catch.ref object to test it

[jcaracappa1]

@andybeet Good catch. updated.