Display::fmt for de::Error is infinitely recursive

[CAD97]

Caused by #208.

  impl fmt::Display for Error {
      fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
          match *self {
              Error::IoError(ref s) => write!(f, "{}", s),
              Error::Message(ref s) => write!(f, "{}", s),
-             Error::Parser(_, pos) => write!(f, "{}: {}", pos, self.description()),
+             Error::Parser(_, pos) => write!(f, "{}: {}", pos, self),
          }
      }
  }

[kvark]

Would be very useful to have a test for this (basically, display printing some type... Also, to have the fix for it separately, as opposed to the giant #222