message: add color & intensity to all lights
  all OSPRay lights have these two parameters
diff: @@ -22,6 +22,8 @@ namespace ospray::sg {
  {
  auto handle = ospNewLight(type.c_str());
  setHandle(handle);
  + createChild("intensity", "float", 1.f);
  + createChild("color", "vec3f", vec3f(1.f));
  }
  NodeType Light::type() const
  @@ -31,6 +33,8 @@ namespace ospray::sg {
  void Light::postCommit() {
  auto &lights = valueAs<cpp::Light>();
  + lights.setParam("intensity", child("intensity").valueAs<float>());
  + lights.setParam("color", child("color").valueAs<vec3f>());
  lights.commit();
  }
  