This also installs symlinks from "zeek" and "bro-config" to a wrapper
script that prints a deprecation warning.
The btests pass, but this is still WIP. broctl renaming is still
missing.
#239
- flow_weird event with name argument value of "routing0_hdr" is raised
for packets containing an IPv6 routing type 0 header because this
type of header is now deprecated according to RFC 5095.
- packets with a routing type 0 header and non-zero segments left
now use the last address in that header in order to associate
with a connection/flow and for calculating TCP/UDP checksums.
- added a set of IPv4/IPv6 TCP/UDP checksum unit tests
In response to feedback from Robin:
- rename "ip_hdr" to "ip4_hdr"
- pkt_hdr$ip6 is now of type "ip6_hdr" instead of "ip6_hdr_chain"
- "ip6_hdr_chain" no longer contains an "ip6_hdr" field, instead
it's the other way around, "ip6_hdr" contains an "ip6_hdr_chain"
- other internal refactoring
