Distributed Interactive Simulation (DIS) ground truth reader

[dalybrown]

I implemented a basic DIS ground truth reader to use with Stone Soup. It's currently built as a python library in a private repository. We'd like to contribute it back to Stone Soup when it's been used a bit more; probably this fall sometime. It makes use of Open DIS for the DIS portion (minus time, which I implemented separately).

Regarding the feature set, we only support (for now) the Entity State PDU sent via multicast, relative timestamps, and the FPW dead reckoning mechanism. We have some unit tests written for it too.

This issue is to remind me to make it public and contribute it back!