Fix duplicate filename issue when sharing traces

Fixed a bug where the filename would be duplicated when sharing a trace. The issue was caused by comparing the name with the trace start date instead of the creation date. Now, the correct comparison ensures the filename is properly assigned.

Author: Andyporras

app/src/main/java/net/osmtracker/gpx/ExportToTempFileTask.java

@@ -36,7 +36,7 @@ public ExportToTempFileTask(Context context, long trackId) {
 			String exportLabelName = PreferenceManager.getDefaultSharedPreferences(context).getString(
 					OSMTracker.Preferences.KEY_OUTPUT_FILENAME_LABEL,	OSMTracker.Preferences.VAL_OUTPUT_FILENAME_LABEL);
 			String trackName = new DataHelper(context).getTrackById(trackId).getName();
-			long date = new DataHelper(context).getTrackById(trackId).getStartDate();
+			long date = new DataHelper(context).getTrackById(trackId).getTrackDate();
 
 			String formattedTrackStartDate = DataHelper.FILENAME_FORMATTER.format(new Date(date));