message: Render underline on empty cells
  This fixes rendering underlines spanning multiple words.
diff: @@ -88,7 +88,7 @@ impl Cell {
  pub fn is_empty(&self) -> bool {
  self.c == ' ' &&
  self.bg == Color::Named(NamedColor::Background) &&
  - !self.flags.contains(INVERSE)
  + !self.flags.intersects(INVERSE | UNDERLINE)
  }
  #[inline]
  