message: Ignore import filename extension case so OBJ = obj, etc.
diff: #include "sg/generator/Generator.h"
  // rkcommon
  #include "rkcommon/os/FileName.h"
  +#include "rkcommon/utility/StringManip.h"
  #include "app/ospStudio.h"
  @@ -141,7 +142,7 @@ inline std::shared_ptr<Importer> getImporter(
  NodePtr root, rkcommon::FileName fileName)
  {
  std::string baseName = fileName.name();
  - auto fnd = importerMap.find(fileName.ext());
  + auto fnd = importerMap.find(rkcommon::utility::lowerCase(fileName.ext()));
  if (fnd == importerMap.end()) {
  std::cout << "No importer for " << fileName << std::endl;
  return nullptr;
  