v3.17.0: OpenTracks

Changes:
- Add icon for kayaking
- Charts draw missing sensor data properly
- Default: show coordinates while recording 

Bugfixes:
- GPX schema corrected
- GPX exported altitude loss as sensor distance
- Statistics not computed correctly if using a speed/distance sensor

Developer:
- Distance/speed value objects
- Replaced communication via SharedPreferences 
- Use non-static service binder
- Use altitude in the code base (instead of elevation)