message: Break out of findFirstChild when found.  Also, optimize search.
  The simple fix would be a single "break" after "found = child.second"
  But, the search was also going deep first, then broad.  To find the importer
  nodes, we need to shallow top-level search first, then deepen as needed.
diff: @@ -72,15 +72,19 @@ OSPSG_INTERFACE void importScene(
  findFirstChild = [&findFirstChild](const sg::NodePtr root,
  const std::string &name) -> sg::NodePtr {
  sg::NodePtr found = nullptr;
  +
  + // Quick shallow top-level search first
  + for (auto child : root->children())
  + if (child.first == name)
  + return child.second;
  +
  + // Next level, deeper search if not found
  for (auto child : root->children()) {
  - if (child.first == name) {
  - found = child.second;
  - } else {
  found = findFirstChild(child.second, name);
  if (found)
  return found;
  }
  - }
  +
  return found;
  };
  