Fix Shadow Filters not having a default constructor and hence not being deserializable.

jme3-core/src/main/java/com/jme3/shadow/AbstractShadowFilter.java

@@ -62,6 +62,12 @@ public abstract class AbstractShadowFilter<T extends AbstractShadowRenderer> ext
     protected T shadowRenderer;
     protected ViewPort viewPort;
 
+    /**
+     * used for serialization
+     */
+    protected AbstractShadowFilter(){
+    }
+    
     /**
      * Abstract class constructor
      *

jme3-core/src/main/java/com/jme3/shadow/DirectionalLightShadowFilter.java

@@ -56,6 +56,16 @@ import java.io.IOException;
  */
 public class DirectionalLightShadowFilter extends AbstractShadowFilter<DirectionalLightShadowRenderer> {
 
+    /**
+     * Used for serialzation.
+     * Use DirectionalLightShadowFilter#DirectionalLightShadowFilter
+     * (AssetManager assetManager, int shadowMapSize, int nbSplits)
+     * instead.
+     */
+    public DirectionalLightShadowFilter() {
+        super();
+    }
+    
     /**
      * Creates a DirectionalLightShadowFilter Shadow Filter More info on the
      * technique at <a

jme3-core/src/main/java/com/jme3/shadow/PointLightShadowFilter.java

@@ -56,6 +56,16 @@ import java.io.IOException;
  */
 public class PointLightShadowFilter extends AbstractShadowFilter<PointLightShadowRenderer> {
 
+    /**
+     * Used for serialization.
+     * Use PointLightShadowFilter#PointLightShadowFilter(AssetManager
+     * assetManager, int shadowMapSize)
+     * instead.
+     */
+    public PointLightShadowFilter() {
+        super();
+    }
+
     /**
      * Creates a PointLightShadowFilter
      *

jme3-core/src/main/java/com/jme3/shadow/PointLightShadowRenderer.java

@@ -63,9 +63,10 @@ public class PointLightShadowRenderer extends AbstractShadowRenderer {
     private Geometry[] frustums = null;
 
     /**
-     * Used for serialization use
+     * Used for serialization.
-     * PointLightShadowRenderer"PointLightShadowRenderer(AssetManager
+     * Use PointLightShadowRenderer#PointLightShadowRenderer(AssetManager
      * assetManager, int shadowMapSize)
+     * instead.
      */
     public PointLightShadowRenderer() {
         super();

jme3-core/src/main/java/com/jme3/shadow/PssmShadowFilter.java

@@ -69,6 +69,16 @@ public class PssmShadowFilter extends Filter {
     private PssmShadowRenderer pssmRenderer;
     private ViewPort viewPort;
 
+    /**
+     * Used for serialization.
+     * Use PssmShadowFilter#PssmShadowFilter(AssetManager
+     * assetManager, int size, int nbSplits)
+     * instead.
+     */
+    public PssmShadowFilter() {
+        super();
+    }
+    
     /**
      * Creates a PSSM Shadow Filter 
      * More info on the technique at <a href="http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html">http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html</a>

jme3-core/src/main/java/com/jme3/shadow/SpotLightShadowFilter.java

@@ -56,6 +56,16 @@ import java.io.IOException;
  */
 public class SpotLightShadowFilter extends AbstractShadowFilter<SpotLightShadowRenderer> {
 
+    /**
+     * Used for serialization.
+     * Use SpotLightShadowFilter#SpotLightShadowFilter(AssetManager assetManager,
+     * int shadowMapSize)
+     * instead.
+     */
+    public SpotLightShadowFilter() {
+        super();
+    }
+    
     /**
      * Creates a SpotLight Shadow Filter
      *