Python parsing

This PR superceeds #1072 so please see that for some discussion of usage. In brief this

- uses @solidgoldbomb's code for generating the uavo definitions on the fly from xml in git
- implements uavtalk in python
- uses that for the parser (and supports both old style log formats and the overo format)
- implements a minimal telemetry interface over TCP socket as a demonstration of how to write a standalone app
- has python/animate.py as a demo of generating nice videos from logged data