Reimplemted the osgUtil::SceneView::setCalcNearFar() functionality to bring

it inline with the CullStack/CullVisitor implementation.  Also added the
setSmallFeatureCullingPixelSize() method and wired them up inside
SceneView.cpp so they set the corresponding CullVisitor paramters.

Intergrated pfImage copying change in the Performer plugin, submission sent in by Ulrich Hertlein

src/osg/CullStack.cpp

@@ -7,7 +7,7 @@ CullStack::CullStack()
 
     _cullingMode = ENABLE_ALL_CULLING;
     _LODBias = 1.0f;
-    _smallFeatureCullingPixelSize = 3.0f;
+    _smallFeatureCullingPixelSize = 2.0f;
     _frustumVolume=-1.0f;
 
 }