start bycatch_fleets

begin creating quantities needed to control characteristics of bycatch
fleets:
Only read  input for the bycatch fleets if there is at least one such
fleet
report1<<"#Bycatch_fleet_input_goes_next"<<endl;
report1<<"#a:  1=use retention curve like other fleets; 2=all
discarded"<<endl;
report1<<"#b:  1=deadfish in MSY, ABC and other benchmark and forecast
output; 2=omit from MSY and ABC (but still include the
mortality)"<<endl;
report1<<"#c:  1=Fmult scales with other fleets; 2=bycatch F constant at
input value; 3=bycatch F form range of years"<<endl;
report1<<"#d:  F or first year of range"<<endl;
report1<<"#e:  last year of range"<<endl;