Remove Cloneable interface

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/FOP_0-20-0_Alt-Design@197811 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/fop/area/Viewport.java

@@ -23,7 +23,7 @@ package org.apache.fop.area;
  * @author pbw
  * @version $Revision$ $Name$
  */
-public interface Viewport extends Cloneable {
+public interface Viewport {
     
     /**
      * Sets the reference-area of this viewport/reference pair