message: Add 'm' key to print material nodes.  Also fix texture "name" type to string.
diff: @@ -83,7 +83,7 @@ namespace ospray::sg {
  sg::createNode(map_name, "texture_2d"));
  auto &tex2D = *sgTex;
  - tex2D["name"].setValue(texName);
  + tex2D["name"].setValue(texName.str());
  sgTex->load(containingPath + texName, preferLinear, nearestFilter);
  @@ -168,6 +168,7 @@ namespace ospray::sg {
  if (param.second != "obj") {
  matType = param.second;
  #if 1 // XXX Accept old OSPRay1.8.5 names
  + // Accept OSPRay 1.8.5 material 'type' names
  if (matType == "Principled")
  matType = "principled";
  if (matType == "CarPaint")
  