Added friend declarations of nested classes to prevent compile problems under VS6.0
Added friend declarations of nested classes to prevent compile problems under VS6.0


koshman86/osg,artoolkit/osg,koshman86/osg,stmh/osg,stmh/osg,XiaoCC/osg,XiaoCC/osg,ntoand/osg,stmh/osg,omega-hub/osg,ntoand/osg,artoolkit/osg,artoolkit/osg,koshman86/osg,stmh/osg,ghub/osg,omega-hub/osg,ghub/osg,ghub/osg,omega-hub/osg,koshman86/osg,ntoand/osg,ntoand/osg,omega-hub/osg,XiaoCC/osg,ghub/osg,XiaoCC/osg,XiaoCC/osg,stmh/osg,artoolkit/osg