Export UniformOrdered

[MathisWellmann]

I'd like to be able to access UniformOrdered from the impl_rand module. I'm not sure why the struct is not exposed by default, but this PR allows for that.
I can imagine why the impl_rand module is not public, but I wonder what the proper way would be for this crate to expose UniformOrdered.
Any pointer are appreciated

[mbrubeck]

Thanks for the patch! I believe you will also need to add documentation comments to the module and its public structs. Feel free to use simple one-liners, like "Uniform random sampler for OrderedFloat".

[mbrubeck]

You could also add something like this to the top of lib.rs:

#[cfg(feature = "rand")]
pub use impl_rand::{UniformNotNan, UniformOrdered};

if you want to expose the structs while keeping the module private.

[MathisWellmann]

Thanks for the input! I decided to go with the second option which is very nice.

[mbrubeck]

Thanks!