close-err - handle errors raised when closing file-like types

Exposes a close method on files (and similar types), to permit finer grained error handling.

Inspired by [close-file], but more generic and works correctly on unix.

For example: ```rust use std::{io, fs::File};

use close_err::Closable;

fn main() -> Result<(), io::Error> { let f = File::create("hi.txt")?;

f.close()?;

Ok(())

} ```