Set main scene graph elements to use thread safe ref/unref by default

include/osg/StateAttribute

@@ -186,7 +186,7 @@ class OSG_EXPORT StateAttribute : public Object
         /** Simple pairing between an attribute type and the member within that attribute type group.*/
         typedef std::pair<Type,unsigned int> TypeMemberPair;
 
-        StateAttribute() {}
+        StateAttribute();
         
         StateAttribute(const StateAttribute& sa,const CopyOp& copyop=CopyOp::SHALLOW_COPY): 
             Object(sa,copyop) {}

src/osg/Drawable.cpp

@@ -245,6 +245,7 @@ void Drawable::flushDeletedVertexBufferObjects(unsigned int contextID,double /*c
 
 
 Drawable::Drawable()
+    :Object(true)
 {
     _boundingBoxComputed = false;
 

src/osg/Image.cpp

@@ -28,6 +28,7 @@ using namespace osg;
 using namespace std;
 
 Image::Image()
+    :Object(true)
 {
     setDataVariance(STATIC); 
 

src/osg/Node.cpp

@@ -53,6 +53,7 @@ namespace osg
 }
 
 Node::Node()
+    :Object(true)
 {
     _boundingSphereComputed = false;
     _nodeMask = 0xffffffff;

src/osg/StateAttribute.cpp

@@ -18,6 +18,13 @@
 
 using namespace osg;
 
+
+StateAttribute::StateAttribute()
+    :Object(true)
+{
+}
+
+
 void StateAttribute::addParent(osg::StateSet* object)
 {
     _parents.push_back(object);

src/osg/View.cpp

@@ -91,6 +91,7 @@ void View::setLightingMode(LightingMode lightingMode)
     if (_lightingMode != NO_LIGHT && !_light) 
     {
         _light = new osg::Light;
+        _light->setThreadSafeRefUnref(true);
         _light->setLightNum(0);
         _light->setAmbient(Vec4(0.00f,0.0f,0.00f,1.0f));
         _light->setDiffuse(Vec4(0.8f,0.8f,0.8f,1.0f));