Move to 2018 edition.

Cargo.toml

@@ -2,6 +2,7 @@
 name = "genetisk"
 version = "0.1.0"
 authors = ["logaritmisk <anders.e.olsson@gmail.com>"]
+edition = "2018"
 
 [dependencies]
 rayon = "1.0"

examples/parabole.rs

@@ -1,7 +1,3 @@
-extern crate genetisk;
-extern crate rand;
-extern crate rayon;
-
 use std::cmp::Ordering;
 
 use rand::distributions::{IndependentSample, Range};

src/lib.rs

@@ -1,7 +1,4 @@
-extern crate rayon;
-
 use rayon::prelude::*;
-
 pub trait Individual: Send {
     type Fitness: Send + Ord;