[m-rev.] for post-commit review: use error_specs in handle_options.m

[Julien Fischer]

On Tue, 13 Oct 2015, Zoltan Somogyi wrote:

> The rationale for this diff is that the code that selects the op_mode
> uses error_util too. We agreed that we should select the op_mode
> as part of option processing, and this prepares for that by eliminating
> a difference that would complicate the review of the diff that does
> that merge.
>
> I was going to move that code to handle_options.m, but I think
> it would be better to move it to a new module (I propose op_mode.m.),
> and also move the code currently in handle_options.m that computes
> the grade and handles the implications of grades to another new module,
> named (say) compute_grade.m. Any opinions, or objections?

Both suggestions are fine by me.

Julien.