message: Add sunsky horizonExtension parameter, requires OSPRay 2.4
diff: @@ -39,15 +39,17 @@ SunSky::SunSky() : Light("sunSky")
  "vec3f",
  "main emission direction of the sun",
  vec3f(0.f, 1.f, 0.f));
  - // XXX enable horizon if it gets exposed in OSPRay
  - //createChild("horizon", "float", 0.01f);
  + createChild("horizonExtension",
  + "float",
  + "extend sky dome by stretching the horizon,\nfraction of the lower hemisphere to cover [0-1]",
  + 0.01f);
  // Set reasonable limits, this will set slider range
  child("albedo").setMinMax(0.f, 1.f);
  child("azimuth").setMinMax(-180.f, 180.f);
  child("elevation").setMinMax(-90.f, 90.f);
  child("turbidity").setMinMax(0.f, 10.f);
  - //child("horizon").setMinMax(0.f, 1.f);
  + child("horizonExtension").setMinMax(0.f, 1.f);
  child("direction").setReadOnly();
  