New extension for Mimkatz v2.0

Behold! This is the guts of a new extension called **Kiwi**, and it embodies the beginnings of a fully fledged container for all of the new goodness that Ben Delpy has baked into Mimkatz v2.0. There's lots of stuff in here so I don't expect this thing to land overnight.

The crux of its use and rationel will be in the MSF side of this PR. So for full details head over there https://github.com/rapid7/metasploit-framework/pull/3121.

This includes all source up to and including revision `r107` from the Mimikatz source repo. All copyright/file headers have been retained to adhere to the licence agreement. Extra code has been added to enable Meterpreter to do a better job of pulling out the details that Mimikatz has extracted.

Instead of doing the CSV-style approach like the original mimikatz extension did, this one actually operates directly on the data structures that this code operates on, which means we don't have to serialise everything to strings prior to sending it over to Metasploit.

This functionality, while inclusive of all the Mimikatz 2.0 code, has not exposed all the functions that are available. For details of the functions that have been exposed, please see the MSF PR.

The MSF PR is here: https://github.com/rapid7/metasploit-framework/pull/3121