message: add shadowCatcherPlane to pathtracer
diff: @@ -38,6 +38,10 @@ PathTracer::PathTracer() : Renderer("pathtracer")
  "bool",
  "allow for alpha blending even if background is seen through refractive objects like glass",
  false);
  + createChild("shadowCatcherPlane",
  + "vec4f",
  + "shadow catcher plane offset and normal (all zeros disable)",
  + vec4f(0));
  child("lightSamples").setMinMax(-1, 1000);
  child("roulettePathLength").setMinMax(0, 1000);
  