minimp3 Rust bindings

Usage example

```toml

Cargo.toml

[dependencies] minimp3 = "0.3" ```

```rust extern crate minimp3;

use minimp3::{Decoder, Frame, Error};

use std::fs::File;

fn main() { let mut decoder = Decoder::new(File::open("audio_file.mp3").unwrap());

loop {
    match decoder.next_frame() {
        Ok(Frame { data, sample_rate, channels, .. }) => {
            println!("Decoded {} samples", data.len() / channels)
        },
        Err(Error::Eof) => break,
        Err(e) => panic!("{:?}", e),
    }
}

} ```