Dronie

[arthurbenemann]

WIP, do not merge

Adds a dronie creation tool.

Here are the things that need to be fixed before merging:

• Display the mission that was created as soon as it's send to the drone, instead of making the user press the "load wp" button.
• Create a dronie button on the flight screen, or some sort of sub-menu.

[arthurbenemann]

I just fixed both remaining issues, and rebased over master. Just waiting for the build to finish before merging.
The UI could be improved a little, because the "dronie" is not a real action button. But I need to make a release with this feature embedded at the moment.