Add default x spacing (half width) for scatter chart as well

MPChartLib/src/main/java/com/github/mikephil/charting/charts/ScatterChart.java

@@ -35,6 +35,9 @@ public class ScatterChart extends BarLineChartBase<ScatterData> implements Scatt
         super.init();
 
         mRenderer = new ScatterChartRenderer(this, mAnimator, mViewPortHandler);
+
+        getXAxis().setSpaceMin(0.5f);
+        getXAxis().setSpaceMax(0.5f);
     }
 
     @Override