Mavlink: Update to HEAD from master branch and add upstream updates f…

[amilcarlucas]

…rom 20200129

This is to test if the upstream mavlink changes break the code

[amilcarlucas]

@tridge All checks passed, this can be merged after ArduPilot/mavlink#127

[tridge]

I've merged the mavlink changes, but I'd like @peterbarker to have a look at the GENERATOR_STATUS change to make sure it doesn't impact on his use case

[peterbarker]

On Tue, 28 Jul 2020, Andrew Tridgell wrote: I've merged the mavlink changes, but I'd like @peterbarker to have a look at the GENERATOR_STATUS change to make sure it doesn't impact on his use case

There's an outstanding PR to use the newly-shaped message. Should be merged in the next day or so.

[amilcarlucas]

@peterbarker can this go in now then? I would like to rebase and prepare the other mavlink PR

[peterbarker]

I'll resolve the generator conflicts in the PR.

Thanks, merged!