Moved the responsibility for finding file to load on to the ReaderWriter plugins,

instead of osgDB::Registry where it original lay.  This has been done to allow
fileName strings to be encode data rather than just file names, such as one
requires when using PagedLOD along with plugins for doing dynamic tesselation.

include/osgDB/ReaderWriter

@@ -61,6 +61,7 @@ class OSGDB_EXPORT ReaderWriter : public osg::Referenced
                 enum ReadStatus
                 {
                     FILE_NOT_HANDLED,
+                    FILE_NOT_FOUND,
                     FILE_LOADED,
                     ERROR_IN_READING_FILE
                 };
@@ -93,6 +94,7 @@ class OSGDB_EXPORT ReaderWriter : public osg::Referenced
                 bool success() const { return _status==FILE_LOADED; }
                 bool error() const { return _status==ERROR_IN_READING_FILE; }
                 bool notHandled() const { return _status==FILE_NOT_HANDLED; }
+                bool notFound() const { return _status==FILE_NOT_FOUND; }
 
             protected:
             

include/osgUtil/TriStripVisitor

@@ -34,7 +34,7 @@ class OSGUTIL_EXPORT TriStripVisitor : public osg::NodeVisitor
         /// default to traversing all children.
         TriStripVisitor() : 
                 osg::NodeVisitor( osg::NodeVisitor::TRAVERSE_ALL_CHILDREN ), 
-                _cacheSize( 24 ),
+                _cacheSize( 16 ),
                 _minStripSize( 2 )
         {}