Course tracking on Android

[1ec5]

As a followup to #2004 and #2068, the Android bindings should have a tracking mode that reports the direction the device is traveling, rather than the direction the device is facing. (Imagine you’re on a train, sitting unfortunately in a seat that’s facing backwards. Or imagine that your phone is mounted on the dash, facing diagonally towards the driver’s seat.)

/cc @ljbade @bleege @incanus

[bleege]

See #2049

[bleege]

I misunderstood this originally. Android should have this.

[ljbade]

@1ec5 in my old location marker (pre move to SDK) code I had a heuristic where if you are stationary then you use compass heading, but if you had GPS motion then it would use GPS heading.

I have suggested to LOST in lostzen/lost#30 that this would be a great feature for the location platform.

Perhaps we can make this configurable.

[ljbade]

Should point out that Google Maps is guilty of the sideways travelling arrow. They always use the compass.