document addition of intrinsic S/R flush calls  + fix ctrl_unpack.F (ALLOW_GENARR3D_CONTROL)
document addition of intrinsic S/R flush calls
 + fix ctrl_unpack.F (ALLOW_GENARR3D_CONTROL)

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