Giving nl an invalid STYLE argument (in --header-numbering=STYLE (-h),

Giving nl an invalid STYLE argument (in --header-numbering=STYLE (-h),
--body-numbering=STYLE (-b), or --footer-numbering=STYLE (-f)) or
FORMAT (--number-format=FORMAT (-n)) would not give a useful diagnostic.

(main): Fix those problems and remove literal quote marks
(e.g., "`%s'") from format string; instead use "%s" in each format
string and `quote (optarg)' as the corresponding argument.
Also, diagnose all invalid command line options before failing.