Easy Progress

> Get progress easily

This example will produce a `ProgressEvent` 20 times.

```rust
// After loop 100 times it will produce 20 ProgressEvent
let mut p = Progress::new("test", 100, 20);

for _i in 0..100 {
    match p.next() {
        Some(event) => {
            println!("{:?}", event);
        }
        None => {}
    }
    std::thread::sleep(std::time::Duration::new(0, 1000 * 100))
}
```