message: correct constness of OSPVariant::toString()
diff: @@ -53,7 +53,7 @@ namespace ospray {
  bool valid() const;
  - std::string toString();
  + std::string toString() const;
  private:
  @@ -353,7 +353,7 @@ namespace ospray {
  return currentType != Type::INVALID;
  }
  - inline std::string OSPVariant::toString()
  + inline std::string OSPVariant::toString() const
  {
  std::stringstream asString;
  asString << "OSPVariant<";
  