Remove usage of FloatMath

This is the same as upstream pull request:
https://bitbucket.org/androidplot/androidplot/pull-request/50

Change-Id: I32064625ac7e2bc5766c95e7fdfb8ad7d18b2864

Examples/DemoApp/src/com/androidplot/demos/TouchZoomExampleActivity.java

diff --git a/Examples/DemoApp/src/com/androidplot/demos/TouchZoomExampleActivity.java b/Examples/DemoApp/src/com/androidplot/demos/TouchZoomExampleActivity.java
index 65c5c71..b7c5a8a 100644
--- a/Examples/DemoApp/src/com/androidplot/demos/TouchZoomExampleActivity.java
+++ b/Examples/DemoApp/src/com/androidplot/demos/TouchZoomExampleActivity.java
@@ -24,7 +24,6 @@
 import android.graphics.Paint;

 import android.graphics.PointF;

 import android.os.Bundle;

-import android.util.FloatMath;

 import android.view.MotionEvent;

 import android.view.View;

 import android.view.View.OnTouchListener;

@@ -202,7 +201,7 @@
     private float spacing(MotionEvent event) {

         float x = event.getX(0) - event.getX(1);

         float y = event.getY(0) - event.getY(1);

-        return FloatMath.sqrt(x * x + y * y);

+        return (float) Math.hypot(x, y);

     }

 }