small patch for ngctl

Hi,

I've made a small patch enhancement for ngctl to support commands 
history via up/down keys when ngctl works under interactive mode.
It was tested on 7.0-CURRENT machine (FreeBSD 7.0-CURRENT #3: Tue May 16 
19:17:48 ULAST 2006).

I thought this feature might be useful for all. I hope my patch follows 
style(9) and it is made against CURRENT, it should also cleanly apply on 
RELENG_6.

I saw a similar enhancement patch in PR 
http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/87352 which adds line 
edit and history support to ngctl(8) via libedit.

My patch uses TERMIOS(4) structure which I thought more portable. Maybe 
I'm wrong.

Please let me know if there is anything that I did wrong.

thanks,

Ganbold