MFC r320268,r320276:

ipfw: dummynet: Add 'G' and 'g' suffix for bandwidth configuration/display

MFC r319900:

sbin/ipfw: strcpy, strncpy => strlcpy

Reported by: Coverity
CID: 1356162, 1356166
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D10662

MFC r317667:
In parse_range() validate both range values instead of checking
the top value twice.

PR: 202295

MFC r302561,302565:
Flush buffer after output. This fixes adding new data to already
printed flows.

PR: 210882
Approved by: re (kib)