pymavlink: include program example

[ES-Alexander]

People regularly struggle to get started with Pymavlink, which isn't surprising given the reasonably poor documentation and examples for it which tend to assume the user is already familiar with mavlink and just happens to want to use pymavlink as their medium for it.

Would be good to include a more comprehensive program example like this gist

[ES-Alexander]

This gist may also be useful to include somewhere, as an example of parsing (and plotting data from) a .tlog file.

Standard log viewing and analysis is better done through tools like UAV Log Viewer, but sometimes it's useful to have free-reign programatic access to telemetry data (e.g. for auto-splitting videos, or creating detailed/custom video overlays, or searching for times where a particular set of conditions were met, etc).

[ES-Alexander]

Good/useful discussion of Pymavlink/MAVLink stuff in this forum thread.

[ES-Alexander]

Step-by-step example of finding and confirming information from a QGC implementation using Pymavlink in this forum thread