[m-rev.] for review: ensure every option is initialized

[Zoltan Somogyi]

The diff itself is boring; I am seeking feedback on the concept.

I am in two minds about this change. On the one hand, it does ensure that
every option is initialized exactly once, which the old code did not,
as evidenced by the fact that it caught an uninitialized option. On the other,
it adds another several hundred lines to an already-too-large module,
and the new version is not as readable as the old, due to the presence
of the option category next to every option. We can ensure unique
initialization only with a switch on the option at the top level, while
I can't see a way to avoid listing the category next to each option
without making the top level switch a switch on the category.
The only resolution I can see is to make the option type
not a single enum type like this:

:- type option ---> opt1; opt2; ...

but a structured type like this:

:- type option ---> category1(opt_in_cat1) ; category2(opt_in_cat2) ...

In this case, the top level switch on the category is also a switch
on a (part of) the option itself. However, I am far from sure whether
such a change is desirable.

Does anyone see any better alternatives?

Zoltan.
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