View source for Calendar

TODO: 
  1. missing context for ##highlight## -> year, month
  2. links
  3. contextual navigation
  4. Апреля 2020 -> Апрель 2020
    * ##strftime()## is not a function that PHP created. It's actually defined in C, and PHP's strftime() is just a thin "wrapper" around it.
    * ICU datetime alternative
  1. on some systems ##ru_RU.UTF-8## can't be set and translates to ##C## -> English

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##~{{calendar}}##
{{calendar}}
 
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##~{{calendar range=12}}##
{{calendar range=12}}