Document and test Vehicle.close

[hamishwillee]

@tcr3dr Can you explain the Vehicle.close semantics - when/why should this be called, and what exactly is the state of the vehicle after doing so? Is this called automatically when a script exits/falls through? etc.

[hamishwillee]

This will be fixed by #384 (adds API reference for method). This is already documented in the migration guide.

[tcr3dr]

Just changing this issue to note there needs to be a few more tests for vehicle.close() to ensure its behavior matches that in the docs.

[hamishwillee]

Or update the docs to make sure they match what it does - I more or less just documented what I thought it should do and was relying on you to catch me being wrong.