or-iterator

Rust iterator which takes two iterators and return not empty one

```rust use or_iterator::OrIterator;

let v1 = vec![1, 2, 3]; let v2 = vec![4, 5]; let or = v1.iter().or(v2.iter()); assert_eq!(3, or.count());

let v1 = vec![]; let v2 = vec![4, 5]; let or = v1.iter().or(v2.iter()); assert_eq!(2, or.count()); ```

Thanks to

Frank Steffahn (https://internals.rust-lang.org/u/steffahn)