Added new Node/Drawable::s/getInitialBound and Node/Drawable::s/getComputeBoundCallback

methods and reimplement computeBound so that it passes back a bounding volume rather
than modifying the local one.

include/osgText/Text

@@ -284,12 +284,12 @@ public:
         return _textureGlyphQuadMap;
     }
 
+    virtual osg::BoundingBox computeBound() const;
+
 protected:
 
     virtual ~Text();
 
-    virtual bool computeBound() const;
-
     Font* getActiveFont();
     const Font* getActiveFont() const;