Added stats collection to new Texture Pool code, and improved TexturePool implementation.

The Texture Pool can be enabled by setting the env var OSG_TEXTURE_POOL_SIZE=size_in_bytes.
Note, setting a size of 1 will result in the TexturePool allocating the minimum number of
textures it can without having to reuse TextureObjects from within the same frame.

src/osgUtil/SceneView.cpp

@@ -1022,6 +1022,9 @@ void SceneView::draw()
     osg::State* state = _renderInfo.getState();
     state->initializeExtensionProcs();
 
+    osg::Texture::TextureObjectManager* tom = osg::Texture::getTextureObjectManager(state->getContextID());
+    tom->newFrame(state->getFrameStamp());
+
     if (!_initCalled) init();
 
     // note, to support multi-pipe systems the deletion of OpenGL display list
@@ -1560,6 +1563,10 @@ void SceneView::draw()
         }
     }
 
+#ifdef REPORT_TEXTURE_MANAGER_STATS
+    tom->reportStats();
+#endif
+
     // osg::notify(osg::NOTICE)<<"SceneView  draw() DynamicObjectCount"<<getState()->getDynamicObjectCount()<<std::endl;
 
 }