Make bad configurations cause errors.

[alvestrand]

This makes configurations with:

• Missing mandatory options
• Options with undefined values return error when one attempts to parse them.

Unrecognized parameters are still allowed.

The "verify_hashnames" script has been renamed to "verify_stored_parameters" and changed a bit to reflect that it also checks that parameters can be parsed.

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[alvestrand]

I signed it!

[googlebot]

CLAs look good, thanks!

[phoglund]

Had some comments.

[phoglund]

lgtm