message: Fix Visual C++ error with range-loop
diff: @@ -187,7 +187,7 @@ bool FileFormatManager::removeFormat(const std::string& identifier)
  if (ids.empty())
  return false;
  - for (unsigned long & id : ids) {
  + for (size_t id : ids) {
  FileFormat* fmt = m_formats[id];
  if (fmt == nullptr)
  