Timezone support: store timezone offset per Track.

When a recording is started the offset of the phone is used.
Timezone is exported to KML and GPX.

Fixes #301.

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

@@ -9,6 +9,8 @@ import android.util.Pair;
 
 import androidx.annotation.NonNull;
 
+import java.time.ZoneOffset;
+
 import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.content.data.Distance;
 import de.dennisguse.opentracks.content.data.Marker;
@@ -47,9 +49,9 @@ class TrackRecordingManager {
         contentProviderUtils = new ContentProviderUtils(context);
     }
 
-    Track.Id start(TrackPoint segmentStartTrackPoint) {
+    Track.Id start(TrackPoint segmentStartTrackPoint, ZoneOffset zoneOffset) {
         // Create new track
-        Track track = new Track();
+        Track track = new Track(zoneOffset);
         trackId = contentProviderUtils.insertTrack(track);
         track.setId(trackId);
 

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

@@ -34,6 +34,7 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import java.time.Duration;
+import java.time.ZoneOffset;
 
 import de.dennisguse.opentracks.R;
 import de.dennisguse.opentracks.TrackListActivity;
@@ -222,7 +223,9 @@ public class TrackRecordingService extends Service implements TrackPointCreator.
         }
 
         // Set recording status
-        Track.Id trackId = trackRecordingManager.start(trackPointCreator.createSegmentStartManual());
+        TrackPoint segmentStartManual = trackPointCreator.createSegmentStartManual();
+        ZoneOffset zoneOffset = ZoneOffset.systemDefault().getRules().getOffset(segmentStartManual.getTime());
+        Track.Id trackId = trackRecordingManager.start(segmentStartManual, zoneOffset);
         updateRecordingStatus(RecordingStatus.record(trackId));
 
         startRecording();