Rewrote osg:Statistics so that it is PrimitiveFunctor as is now completely

decoupled from osg::Drawable.  The Drawable::getStats() virtual method
no longer exists.

Updated the Viewer to use the osg::Statistics incarnation and reformated stats
to clean it up.

src/osgUtil/RenderStage.cpp

@@ -1,8 +1,10 @@
 #include <stdio.h>
 #include <osg/Notify>
+#include <osg/Statistics>
 
 #include <osgUtil/RenderStage>
 
+
 using namespace osg;
 using namespace osgUtil;