In the ChartSettingsDialog, update whether to display speed

or pace when calling onPrepareDialog.

Change the x_axis.png and y_axis.png to white foreground
so they show up on the black background.

Clean up chart_settings.xml
- no need to specify minWidth by placing the title
  inside a TableLayout
- align text to the bottom of the image

MyTracks/src/com/google/android/apps/mytracks/ChartActivity.java

@@ -240,6 +240,7 @@ public class ChartActivity extends Activity implements TrackDataListener {
 
   private void prepareSettingsDialog(ChartSettingsDialog settingsDialog) {
     settingsDialog.setMode(chartView.getMode());
+    settingsDialog.setDisplaySpeed(reportSpeed);
     for (int i = 0; i < ChartView.NUM_SERIES; i++) {
       settingsDialog.setSeriesEnabled(i, chartView.isChartValueSeriesEnabled(i));
     }