Added osgSim library which encapulsulates light points.

Added osglightpoint demo.

include/osgSim/Export

@@ -0,0 +1,40 @@
+//C++ header - Open Scene Graph Simulation - Copyright (C) 1998-2002 Robert Osfield
+// Distributed under the terms of the GNU General Public License (GPL)
+// as published by the Free Software Foundation.
+//
+// All software using osgSim must be GPL'd or excempted via the 
+// purchase of the Open Scene Graph Professional License (OSGPL)
+// for further information contact robert@openscenegraph.com.
+
+#ifndef OSGSIM_EXPORT_
+#define OSGSIM_EXPORT_ 1
+
+#if defined(WIN32) && !(defined(__CYGWIN__) || defined(__MINGW32__))
+    #pragma warning( disable : 4244 )
+    #pragma warning( disable : 4251 )
+    #pragma warning( disable : 4275 )
+    #pragma warning( disable : 4786 )
+    #pragma warning( disable : 4290 )
+#endif
+
+#if defined(_MSC_VER) || defined(__CYGWIN__) || defined(__MINGW32__) || defined( __BCPLUSPLUS__)  || defined( __MWERKS__)
+    #  ifdef OSGSIM_LIBRARY
+    #    define OSGSIM_EXPORT   __declspec(dllexport)
+    #  else
+    #    define OSGSIM_EXPORT   __declspec(dllimport)
+    #  endif /* SG_LIBRARY */
+#else
+    #  define OSGSIM_EXPORT
+#endif  
+
+/* Define NULL pointer value */
+
+#ifndef NULL
+#ifdef  __cplusplus
+#define NULL    0
+#else
+#define NULL    ((void *)0)
+#endif
+#endif
+
+#endif