message: Fallback to Qt's X-Language in language detection
  If the standard Language header is missing, but Qt's X-Language
  extension is present, use the latter instead of heuristics.
diff: @@ -379,12 +379,22 @@ void Catalog::HeaderData::ParseDict()
  }
  // Parse language information, with backwards compatibility with X-Poedit-*:
  + Lang = Language();
  wxString languageCode = GetHeader("Language");
  if (!languageCode.empty())
  {
  Lang = Language::TryParse(languageCode.ToStdWstring());
  }
  - else
  +
  + if (!Lang.IsValid())
  + {
  + // try looking for non-standard Qt extension
  + languageCode = GetHeader("X-Language");
  + if (!languageCode.empty())
  + Lang = Language::TryParse(languageCode.ToStdWstring());
  + }
  +
  + if (!Lang.IsValid())
  {
  wxString X_Language = GetHeader("X-Poedit-Language");
  wxString X_Country = GetHeader("X-Poedit-Country");
  