0.01: First release
0.02: Bugfix time: Reset minutes to 0 when hitting 60
0.03: Fix distance >=10 km (fix #529)
0.04: Use offscreen buffer for flickerless updates
0.05: Complete rewrite. New UI, GPS & HRM Kalman filters, activity logging
0.06: Reading HDOP directly from the GPS event (needs Espruino 2v07 or above)
0.07: Fixed GPS update, added guards against NaN values
0.08: Fix issue with GPS coordinates being wrong after the first one
0.09: Another GPS fix (log raw coordinates - not filtered ones)
0.10: Removed kalman filtering to allow distance log to work
      Only log data every 5 seconds (not 1 sec)
      Don't create a file until the first log entry is ready
      Add labels for buttons