pass-modelEnd flag as argument, from forward_step to diagnostics_write:  in case useSIGREG, will write (averaged) diagnostics (if dumpAtLast) before  writing pickups and stopping.
pass-modelEnd flag as argument, from forward_step to diagnostics_write:
 in case useSIGREG, will write (averaged) diagnostics (if dumpAtLast) before
 writing pickups and stopping.

altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h