message: Removes redundant imports on error.rs
diff: //! Error types and conversion functions.
  -
  -use std;
  use std::error::Error;
  use std::fmt;
  use std::sync::Arc;
  -use gfx;
  -use glutin;
  -use winit;
  -
  -use gilrs;
  -use image;
  -use lyon;
  use rodio::decoder::DecoderError;
  -use toml;
  -use zip;
  /// An enum containing all kinds of game framework errors.
  #[derive(Debug, Clone)]
  