add axis label rotation to style manager

xchart/src/main/java/com/xeiam/xchart/StyleManager.java

@@ -123,6 +123,8 @@ public class StyleManager {
   private double axisTickSpacePercentage;
   private TextAlignment xAxisLabelAlignment = TextAlignment.Centre;
   private TextAlignment yAxisLabelAlignment = TextAlignment.Left;
+  private int xAxisLabelRotation = 0;
+  private int yAxisLabelRotation = 0;
 
   // Chart Plot Area ///////////////////////////////
   private boolean isPlotGridLinesVisible;
@@ -906,6 +908,26 @@ public class StyleManager {
     this.yAxisLabelAlignment = yAxisLabelAlignment;
   }
 
+  public int getXAxisLabelRotation() {
+
+    return xAxisLabelRotation;
+  }
+
+  public void setXAxisLabelRotation(int xAxisLabelRotation) {
+
+    this.xAxisLabelRotation = xAxisLabelRotation;
+  }
+
+  public int getYAxisLabelRotation() {
+
+    return yAxisLabelRotation;
+  }
+
+  public void setYAxisLabelRotation(int yAxisLabelRotation) {
+
+    this.yAxisLabelRotation = yAxisLabelRotation;
+  }
+
   // Chart Plot Area ///////////////////////////////
 
   /**