title: ClassCastException when using simonvt number picker
body: <p>I'm trying to use simonvt number picker. I have added the library succesfully to my project and I have run sample project with library successfully.
  But in my project I get this exception :</p>
  
  <blockquote>
    <p>12-01 21:39:48.543: E/AndroidRuntime(987): java.lang.RuntimeException: Unable to start >activity ComponentInfo{com.tekna.digiguide/com.tekna.digiguide.KayitHourPickerActivity}: >java.lang.ClassCastException: net.simonvt.widget.NumberPicker</p>
  </blockquote>
  
  <p>Can anyone help?</p>
  
  <p>my xml file</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="center"
      android:orientation="vertical" &gt;
  
      &lt;net.simonvt.widget.NumberPicker
          android:id="@+id/numberPicker"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content" /&gt;
  
      &lt;Button
          android:id="@+id/buttonPickerEkle"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Button" /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>and my actvity</p>
  
  <pre><code>protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
  
          setContentView(R.layout.pickerlayout);
  
          final NumberPicker np = (NumberPicker) findViewById(R.id.numberPicker);
          np.setMaxValue(24);
          np.setMinValue(1);
          np.setFocusable(true);
  
          np.setFocusableInTouchMode(true);
      }
  </code></pre>