feat(#313): Add support for conversion of multiple exported sessions.

[alxbl]

This pull request adds the ability to convert multiple sessions inside of an exported PDU PCAP. It fixes #313.

This is done by parsing the EXPORTED_PDU header (in a very ad-hoc way, right now) with a custom Exported layer to retrieve the ip.src, tcp.sport, ip.dst, and tcp.dport tags in the header and modifying the tcp_both session extraction code to use the Exported layer.

I say the layer is ad-hoc because EXPORTED_PDU's tags are an arbitrary list of tags with the following form:

tagIdentifier (2B)
tagLength (2B)
tagBytes (<tagLength>B)
[.... repeat until tagEnd ...]
tagEnd ("\x00\x00")
tagLength ("\x00\x00")

But right now what I'm doing is hardcoding the list of tags that I've seen in typical exported RDP L7 captures, so it might fail for non-standard exports.

We can fix that when/if it happens. In general if it fails, it's probably because the pcap wasn't exported properly.

[obilodeau]

Not much more luck here. I'll investigate the JSON output deeper then.

[obilodeau]

Just pushed a rebase on master. I manually handled conflicts but the new InetAddress code is still not using Exported since I fixed similar problems in my own fixes on top of the #366 PR. More stuff is coming.

[obilodeau]

Another interactive rebase to make everything neat and avoid a squash commit