v3.27.0: OpenTracks

Changes:
- Voice annoucements: add 100m, 200m, and 500m
- Interval: add 100m and 500m
- Clock shows now also seconds
- GPX, KML, KMZ: export and import horizontal accuracy
- GPX: export cumulative distance via clustrust extension
- CSV: basic export (TrackPoints only; not for backup)
- Workaround for Tickr X as it reports SPM instead of RPM 

Bugfixes:
- Adhere to recording distance interval;
  TrackPoints were recorded although they were too close
- Prevent crash on stop re