Merge r247666, r247712, r247811.

Fix ipfw table argument parsing/printing.
Fix style.

PR:		kern/175909
Submitted by:	Daniel Hagerty <hag@linnaean.org>

Implement buffer size checking in ipfw(8) add cmd.

PR:		bin/65961
Submitted by:	Eugene Grosbein <eugen@grosbein.pp.ru>

Do not suddenly fail on some rulesets if -n (syntax check only) is specified
and ipfw(4) module is not loaded.
Merge r248112.

Document netstat -Q flags meaning.