Support multiple network sizes; fix radvd bug; shell lint (#3)
Support multiple network sizes; fix radvd bug; shell lint (#3)

We always assumed /64, but some ISPs give out /56s, so lets make sure
we support multiple sizes.

Also shellcheck the entire thing.

Finally fix a bug from when dnsmasq was added that through errors
on radvd systems.

Signed-off-by: Phil Dibowitz <e888d2bd6f13f82caa51a37c03d034c76f661ba3@ipom.com>
jaymzh/v6-gw-scripts