This adds support for slightly less output than is normally provided by
'ip link show' and 'ip addr show'.  This is a bit better when you have a
host with lots of interfaces.  Sample output:

$ ip -br link show
lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
p2p1             UP             08:00:27:ee:0b:3b <BROADCAST,MULTICAST,UP,LOWER_UP>
p7p1             UP             08:00:27:9d:62:9f <BROADCAST,MULTICAST,UP,LOWER_UP>
p8p1             DOWN           08:00:27:dc:d8:ca <NO-CARRIER,BROADCAST,MULTICAST,UP>
p9p1             UP             08:00:27:76:d9:75 <BROADCAST,MULTICAST,UP,LOWER_UP>
p7p1.100@p7p1    UP             08:00:27:9d:62:9f <BROADCAST,MULTICAST,UP,LOWER_UP>

$ ip -br -4 addr show
lo               UNKNOWN        127.0.0.1/8
p2p1             UP             192.168.56.2/24
p7p1             UP             70.0.0.1/24
p8p1             DOWN           80.0.0.1/24
p9p1             UP             10.0.5.15/24
p7p1.100@p7p1    UP             200.0.0.1/24

$ ip -br -6 addr show
lo               UNKNOWN        ::1/128
p2p1             UP             fe80::a00:27ff:feee:b3b/64
p7p1             UP             7000::1/8 fe80::a00:27ff:fe9d:629f/64
p8p1             DOWN           8000::1/8
p9p1             UP             fe80::a00:27ff:fe76:d975/64
p7p1.100@p7p1    UP             fe80::a00:27ff:fe9d:629f/64

$ ip -br addr show p7p1
p7p1             UP             70.0.0.1/24 7000::1/8 fe80::a00:27ff:fe9d:629f/64

v2: Now with color support!
v3: Better field width estimation (except netdev names to keep output at a
decent width) and whitespace fixup.
Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>