Mark OLESEN authored Oct 04, 2023 and Andrew Heather committed Oct 11, 2023

- support std::string_view (c++17) or span view (older c++) of stream
  buffer contents. This simplifies formatting + reparsing.

  Example,

      OCharStream os;
      os << ...;

      ISpanStream is(os.view());
      is >> ...;

- additional release() method for ICharStream, OCharStream
  that returns the contents as a DynamicList<char> and resets the stream.

- provide a str() method for API compatibility with older
  std::ostringstream etc.