Avoid creating flakey clone

Author: monkstone

src/org/jbox2d/common/Mat22.java

@@ -32,7 +32,9 @@
  */
 public class Mat22 implements Serializable {
 
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = -3851554186221722070L;
+
+    
 
     public final Vec2 ex, ey;
 
@@ -103,16 +105,6 @@ public final Mat22 set(final float exx, final float col2x, final float exy, fina
         return this;
     }
 
-    /**
-     * Return a clone of this matrix. djm fixed double allocation
-     *
-     * @return
-     */
-    // @Override // annotation omitted for GWT-compatibility
-    @Override
-    public final Mat22 clone() {
-        return new Mat22(ex, ey);
-    }
 
     /**
      * Set as a matrix representing a rotation.