Bump Rust to 2021 edition

src/pix/canvas.rs

@@ -5,10 +5,10 @@ use std::time::Duration;
 
 use image::DynamicImage;
 
-use painter::handle::Handle;
-use painter::painter::Painter;
-use pix::client::Client;
-use rect::Rect;
+use crate::painter::handle::Handle;
+use crate::painter::painter::Painter;
+use crate::pix::client::Client;
+use crate::rect::Rect;
 
 /// A pixflut instance
 pub struct Canvas {

src/pix/client.rs

@@ -1,14 +1,11 @@
-extern crate bufstream;
-extern crate regex;
-
 use std::io::prelude::*;
 use std::io::{Error, ErrorKind};
 use std::net::TcpStream;
 
-use self::bufstream::BufStream;
-use self::regex::Regex;
+use bufstream::BufStream;
+use regex::Regex;
 
-use color::Color;
+use crate::color::Color;
 
 // The default buffer size for reading the client stream.
 // - Big enough so we don't have to expand