`Bson` doesn't uphold `Eq`'s reflexivity guarantee

[tyilo]

According to the Eq documentation any type implementing the trait should ensure that all values are reflexive.

This is not the case for Bson even though it implements Eq:

fn main() {
    let v = bson::Bson::Double(f64::NAN);
    assert_eq!(v, v);
}

thread 'main' (2304097) panicked at src/main.rs:3:5:
assertion `left == right` failed
  left: Double(NaN)
 right: Double(NaN)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Either the Eq implementation should be removed or Bson::eq should compare the bits of f64's (or something similar).