weather 6.x-5.1

Changes:

• Optionally calculate windchill ("Feels like temperature")
• Add Kathmandu, Nepal to supported ICAO codes. Thanks to sarmiluv for the report. Closes: #330026: Kathmandu is missing
• Make the ICAO parser more robust:
  • Recognize crossed out dewpoints (e.g. '16/XX') and spaces between cloud conditions (e.g. 'FEW 025')
  • If no information about vertical visibility ('VV///') is available, the data will be rendered as overcast
• Add new translation to Romanian. Thanks to Füleki Miklós.
• Add new translation to Greek. Thanks to Vasileios Lourdas.
• Rename Danish translation from dk.po to da.po
• Translation updates for:
  • German, thanks to Tobias Quathamer.
  • Russian, thanks to Vasili Pinchuk and Alexander Lavrinenko. Closes: #337306: Translated into Russian
  • Dutch, thanks to Martin Niewzwaag.
  • Spanish, thanks to Marcos Goyeneche.
  • Czech, thanks to Marek Drápal.
  • Polish, thanks to Adrian Siemieniak.
  • Hungarian, thanks to Füleki Miklós.
  • Brazilian Portuguese, thanks to Ramon Magnus.
  • Danish, thanks to Morten Wulff.