[Wien] NON-ZERO forces for zinc-blend GaAs

[Laurence Marks]

>
> AUTHORS: If  "-cc 0.00001 -fc 0.05" is used, and it happens that force
> convergence is reached earlier than charge convergence, then all
> iterations after reaching force convergence use FOR instead of TOT. For
> big cases, this consumes a lot of extra computing time. It would be
> helpful if when specifying -fc plus another convergence criterium, FOR
> is used only after satisfying *all* convergence criteria.

In principle FOR is only set once all convergence criteria are set.
Unfortunately in the next cycle the criteria may fail, particularly if
:PLANE is not converged well (which I am going to suggest to Peter be
added a future release).