specl: extract rather than hardcode default option specs.
specl: extract rather than hardcode default option specs.

* specl/optparse.lua (set_handler): Diagnose multiple handlers.
(new): Loop over option specification lines in the parsed help
text, and set up default option handlers to match.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/specl