message: Add a camera scene graph node
diff: #include <visionaray/math/vector.h>
  #include <visionaray/aligned_vector.h>
  #include <visionaray/spectrum.h>
  +#include <visionaray/thin_lens_camera.h>
  #if VSNRAY_COMMON_HAVE_PTEX
  #include "ptex.h"
  @@ -229,6 +230,19 @@ protected:
  };
  +//-------------------------------------------------------------------------------------------------
  +// Camera node
  +//
  +
  +class camera : public node, public thin_lens_camera
  +{
  +public:
  +
  + VSNRAY_SG_NODE
  +
  +};
  +
  +
  //-------------------------------------------------------------------------------------------------
  // Transform node
  //
  