[m-rev.] for review: warn about unneeded initial and final state vars

[Zoltan Somogyi]

For review by anyone. I will update the user guide once
the new documentation in options.m is approved.

Much of the diff consists of me acting on the new warnings,
so you can see how useful they are. I have not yet acted on
*all* such warnings, because this diff is large enough already;
that will come later.

Zoltan
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