Added the patched verions VisualStudio's langext.dat file, which can be used

to replace VisualStudio standard one, this enabled VS to reconginse OSG
header files as C++ files.

VisualStudio/LANGEXT.DAT

@@ -0,0 +1,141 @@
+langext.dat - Map explicit filename to a language
+[C/C++]
+algorithm bitset cassert cctype cerrno cfloat ciso646 climits clocale cmath complex
+csetjmp csignal cstdarg cstddef cstdio cstdlib cstring ctime cwchar cwctype
+deque exception fstream functional iomanip ios iosfwd iostream istream iterator
+limits list locale map memory new numeric ostream queue
+set sstream stack stdexcept streambuf string strstream typeinfo utility valarray vector
+xcomplex xios xiosbase xlocale xlocinfo xlocmon xlocnum xloctime xmemory xstddef xstring xtree xutility
+AlphaFunc
+AnimationPath
+Billboard
+BoundingBox
+BoundingSphere
+BoundsChecking
+Camera
+ClippingVolume
+ClipPlane
+ColorMask
+ColorMatrix
+CopyOp
+CullFace
+Depth
+DisplaySettings
+Drawable
+EarthSky
+Export
+Fog
+FrameStamp
+FrontFace
+Geode
+GeoSet
+GL
+GLExtensions
+GLU
+Group
+Image
+Impostor
+ImpostorSprite
+Light
+LightModel
+LightSource
+LineSegment
+LineStipple
+LineWidth
+LOD
+Material
+Math
+Matrix
+MemoryAdapter
+mem_ptr
+Node
+NodeCallback
+NodeVisitor
+Notify
+Object
+Plane
+Point
+PolygonMode
+PolygonOffset
+PositionAttitudeTransform
+Quat
+Referenced
+ref_ptr
+ShadeModel
+State
+StateAttribute
+StateSet
+Statistics
+Stencil
+Switch
+TexEnv
+TexGen
+TexMat
+Texture
+TextureCubeMap
+Timer
+Transform
+Transparency
+Types
+Vec2
+Vec3
+Vec4
+Version
+Viewport
+AppVisitor
+CameraManipulator
+CullViewState
+CullVisitor
+DepthSortedBin
+DisplayListVisitor
+DisplayRequirementsVisitor
+DriveManipulator
+Export
+FlightManipulator
+GUIActionAdapter
+GUIEventAdapter
+GUIEventHandler
+InsertImpostorsVisitor
+IntersectVisitor
+Optimizer
+RenderBin
+RenderGraph
+RenderLeaf
+RenderStage
+RenderStageLighting
+RenderToTextureStage
+SceneView
+SceneViewManipulator
+SmoothingVisitor
+StateSetManipulator
+Tesselator
+TrackballManipulator
+TransformCallback
+TriStripVisitor
+Version
+DotOsgWrapper
+DynamicLibrary
+Export
+Field
+FieldReader
+FieldReaderIterator
+FileNameUtils
+FileUtils
+Input
+Output
+ReaderWriter
+ReadFile
+Registry
+Version
+WriteFile
+Export
+glut
+GLUTEventAdapter
+Version
+Viewer
+Window
+Export
+Font
+Paragraph
+Text
+Version