document changes in eesupp & genmake2 (etime), tools/tst_2+2, pkg/dic (rm USE_ATMOSCO2)  and new flag to apply EXCH to U,V earlier.
document changes in eesupp & genmake2 (etime), tools/tst_2+2, pkg/dic (rm USE_ATMOSCO2)
 and new flag to apply EXCH to U,V earlier.

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