imply_option 0.1.1

An implementation of [this RFC](https://github.com/rust-lang/rfcs/pull/2180). Provides a single `trait` which allows the construction of an `Option` based on a bool value. ``` extern crate imply_option; use imply_option::*; fn main() { let pass = true; assert_eq!(pass.then(1), Some(1)); assert_eq!(pass.then_do(|| 1), Some(1)); let fail = false; assert_eq!(fail.then(1), None); } ```