Simple extension trait for Option
for working with tupleized results.
```rust extern crate mcoffintupleext; use mcoffintupleext::OptionExt;
fn main() {
let first = Some(1usize);
asserteq!(first.andtup(first), Some((1usize, 1usize)));
asserteq!(first.andtup(Some(2usize)), Some((1usize, 2usize)));
asserteq!(first.andtup::
let v = first.and_then_tup(|_| Some("foo".to_string()));
assert!(v.is_some());
let (fst, snd) = v.unwrap();
assert_eq!(fst, 1);
assert_eq!(&snd, "foo");
} ```