feat: impl Borrow for OrderedFloat<f32> and OrderedFloat<f64>

[tisonkun]

Compiled tells the trivial result. No need for trivial tests.

This follows:

impl Borrow<f32> for NotNan<f32> {
    #[inline]
    fn borrow(&self) -> &f32 {
        &self.0
    }
}

impl Borrow<f64> for NotNan<f64> {
    #[inline]
    fn borrow(&self) -> &f64 {
        &self.0
    }
}

cc @mbrubeck

[mbrubeck]

Unfortunately, this may cause problems with type inference in some programs:

#105

I'm not sure what to do here. What is the main use case for this impl?

[tisonkun]

What is the main use case for this impl?

It's not easy to describe but I use impl From<OrderedFloat<f64>> for f64 to workaround my use case.

So no need for this patch any more.

Close as there is a blocker.