v3.3.1: OpenTracks

Changes:
- Android 10: on uninstall allow to keep app data
- Introduced Dashboard API: map icon can be used to open current track in external app
  (requires installation of another app like OSMDashboard)

Bugfix:
- App label was broken (introduced in v3.3.0)

Developer:
- Documentation for Dashboard API can be found in README_DEVELOPER.md