[Mitgcm-support] time_ave output

[mitgcm-support at dev.mitgcm.org]

Hello,

I have check-in few modifications that enable to use again 
the time average diagnostics (broken after ckp35).
(also move the I/O at a different place in forward_step).

I have not yet modified the names of the CPP kee and routines
to make this "time average" part of the code as a package.
(this is the next step)

Jean-Michel