Updates to the flush rendering objects function calls to allow for

managment of amount of time available to do gl delete's.  This control is
required for constant frame rate applications.

src/osg/Timer.cpp

@@ -24,6 +24,13 @@ using namespace osg;
 //
 // all the rest of the timer methods are implemented within the header.
 
+
+const Timer* Timer::instance()
+{
+    static Timer s_timer;
+    return &s_timer;
+}
+
 #ifdef WIN32
 
     #include <sys/types.h>