Interval stats: while user is recording a track intervals are refreshed every 5 seconds.

Interval stats: completed the list of split intervals: 1, 2, 3, 4, 5, 10, 20 or 50 km or mi.
Fixes #87.

src/main/java/de/dennisguse/opentracks/fragments/IntervalsRecordingFragment.java

@@ -15,6 +15,7 @@ import androidx.lifecycle.ViewModelProvider;
 
 import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.util.PreferencesUtils;
+import de.dennisguse.opentracks.util.UnitConversions;
 import de.dennisguse.opentracks.viewmodels.IntervalStatistics;
 import de.dennisguse.opentracks.viewmodels.IntervalStatisticsModel;
 import de.dennisguse.opentracks.views.IntervalListView;
@@ -27,6 +28,8 @@ public class IntervalsRecordingFragment extends Fragment implements IntervalList
 
     private static final String TAG = IntervalsRecordingFragment.class.getSimpleName();
 
+    private static final long UI_UPDATE_INTERVAL = 5 * UnitConversions.ONE_SECOND_MS;
+
     private IntervalStatisticsModel viewModel;
     private IntervalReverseListView intervalListView;
 
@@ -37,7 +40,7 @@ public class IntervalsRecordingFragment extends Fragment implements IntervalList
         public void run() {
             if (!stopped) {
                 updateIntervals();
-                intervalHandler.postDelayed(intervalRunner, 5000);
+                intervalHandler.postDelayed(intervalRunner, UI_UPDATE_INTERVAL);
             }
         }
 

src/main/java/de/dennisguse/opentracks/viewmodels/IntervalStatisticsModel.java

@@ -72,7 +72,9 @@ public class IntervalStatisticsModel extends AndroidViewModel {
         OPTION_3(3),
         OPTION_4(4),
         OPTION_5(5),
-        OPTION_10(10);
+        OPTION_10(10),
+        OPTION_20(20),
+        OPTION_50(50);
 
         private int value;