Improve GPS support

[dirkjanfaber]

• Show the cardinal direction for the course.
• Add a proper unit for the altitude (meter / feet)

Note that there is also a patch on veutil for altitude support.

[DanielMcInnes]

Hi @dirkjanfaber , is there an installation where I can test this?

[dirkjanfaber]

Send info on the installation via Slack.

Another thing to note is that the Venus settings currently doesn't have a general setting for Altitude (via venus-platform). To me it would seem logical to add it as /System/Units/Altitude, comparable with the Kelvin / Celsius TemperatureUnit here: https://github.com/victronenergy/venus-platform/blob/master/src/application.cpp#L237

Alternative is to add it as /Gps/AltitudeUnit in line with the existing SpeedUnit, here: https://github.com/victronenergy/venus-platform/blob/master/src/application.cpp#L192.

I don't have a strong opinion for either option. A bit far fetched, but I can image that altitude might also be used to indicate on which altitude the solar panels, irradiance sensor or some wind generator has been installed.

It is also a bit awkward that the gps'es don't appear under the device list, as I would have expected initially. But didn't touch that as I also don't want to make this PR bigger than it needs to be.

[DanielMcInnes]

Is this currently supported by venus-platform?

[dirkjanfaber]

That line 293 you mean? No, it isn't supported there yet. It could be that /Settings/System/Gps/AltitudeUnit is the better option.

See #1841 (comment).

[DanielMcInnes]

I expect we will wait for platform support before merging these changes

[dirkjanfaber]

Initiated a change there. Lets indeed wait until that has been merged before continuing this PR.