message: Fix rust 1.24 compatibility
diff: use num_traits::Zero;
  use std::io;
  use std::marker::PhantomData;
  -use std::ops::{Deref, DerefMut, Index, IndexMut};
  +use std::ops::{Deref, DerefMut, Index, IndexMut, Range};
  use std::path::Path;
  use std::slice::{Chunks, ChunksMut};
  @@ -395,7 +395,7 @@ where
  }
  #[inline(always)]
  - fn pixel_indices(&self, x: u32, y: u32) -> Option<std::ops::Range<usize>> {
  + fn pixel_indices(&self, x: u32, y: u32) -> Option<Range<usize>> {
  if x >= self.width || y >= self.height {
  return None
  }
  @@ -406,7 +406,7 @@ where
  }
  #[inline(always)]
  - unsafe fn unsafe_pixel_indices(&self, x: u32, y: u32) -> std::ops::Range<usize> {
  + unsafe fn unsafe_pixel_indices(&self, x: u32, y: u32) -> Range<usize> {
  let no_channels = <P as Pixel>::channel_count() as usize;
  // If in bounds, this can't overflow as we have tested that at construction!
  let min_index = (y as usize*self.width as usize + x as usize)*no_channels;
  