message: [terminal] Line: fixes toUtf() implementation.
diff: #include <algorithm>
  #include <iostream>
  #include <optional>
  +#include <sstream>
  #include <tuple>
  #include <utility>
  @@ -107,23 +108,20 @@ Line::Line(int _numCols, std::string_view const& _s, Flags _flags) :
  string Line::toUtf8() const
  {
  - string s;
  - s.resize(size() * 4);
  - auto t = s.data();
  + std::stringstream sstr;
  for (Cell const& cell : crispy::range(begin(), next(begin(), size())))
  {
  if (cell.codepointCount() == 0)
  {
  - *t++ = ' '; // NB: empty cells are represented as space.
  + sstr << ' ';
  }
  else
  {
  for (char32_t codepoint : cell.codepoints())
  - t = unicode::encoder<char>{}(codepoint, t);
  + sstr << unicode::convert_to<char>(codepoint);
  }
  }
  - s.resize(std::distance(s.data(), t));
  - return s;
  + return sstr.str();
  }
  string Line::toUtf8Trimmed() const
  