cpuio: Rust wrapper for inb, outb, etc., instructions

This library is intended to be run on bare metal, and it only depends on the core library.

To use this, add it to your Cargo.toml file and call cpuio::Port::new to create a port, being sure to specify u8, u16 or u32 depending on the size data supported by the port.

```rust extern crate cpuio;

use cpuio::Port;

fn main() { // Create a port pointing at 0x60, the address of the PS/2 keyboard // port on x86 hardware. This is an unsafe operation because many // ports can be used to reconfigure your underlying hardware, and // it's the responsiblity of the port creator to make sure it's // used safely. let mut keyboard: Port = unsafe { Port::new(0x60) };

// Read a single scancode from a PS/2 keyboard.  If you run this as
// an ordinary user, it will fail with a SIGSEGV.
println!("scancode: {}", keyboard.read());

} ```

The constructor Port::new is available as a const fn, which allows you to configure a port at compile time.

Licensing

Licensed under the Apache License, Version 2.0 or the MIT license, at your option.