Introduced use of ref_ptr<> and private destructor to tighen up memory management and avoid users attempting to inappropriately delete TexCoordRange.

include/osgDB/ImageOptions

@@ -120,6 +120,8 @@ class OSGDB_EXPORT ImageOptions : public osgDB::Options
             }
 
             double _x,_y,_w,_h;
+        protected:
+            virtual ~TexCoordRange() {}
         };