Bugfix: TrackListActivity couldn't stop and restart sensors.

Part of #1780.

src/main/java/de/dennisguse/opentracks/TrackListActivity.java

@@ -158,6 +158,7 @@ public class TrackListActivity extends AbstractTrackDeleteActivity implements Co
             } else {
                 if (gpsStatusValue.isGpsStarted()) {
                     recordingStatusConnection.unbindAndStop(this);
+                    recordingStatusConnection.startConnection(this); //TODO We need to stay listening!
                 } else {
                     new TrackRecordingServiceConnection((service, connection) -> {
                         service.tryStartSensors();

src/main/java/de/dennisguse/opentracks/services/TrackRecordingService.java

@@ -125,6 +125,9 @@ public class TrackRecordingService extends Service implements TrackPointCreator.
         if (isRecording()) {
             endCurrentTrack();
         }
+        if (isSensorStarted()) {
+            stopSensors();
+        }
 
         PreferencesUtils.unregisterOnSharedPreferenceChangeListener(this);
 
@@ -248,6 +251,7 @@ public class TrackRecordingService extends Service implements TrackPointCreator.
         stopForeground(true);
         notificationManager.cancelNotification();
         wakeLock = SystemUtils.releaseWakeLock(wakeLock);
+        gpsStatusObservable.postValue(STATUS_GPS_DEFAULT);
     }
 
     @Override