message: Changed the Rows/RowsMut iters to use BatchExact/BatchExactMut
  This change makes sense because all rows will have the same length.
  And there could be possible auto-vectorization benefits.
diff: @@ -3,7 +3,7 @@ use num_traits::Zero;
  use std::marker::PhantomData;
  use std::ops::{Deref, DerefMut, Index, IndexMut, Range};
  use std::path::Path;
  -use std::slice::{Chunks, ChunksMut, ChunksExact, ChunksExactMut};
  +use std::slice::{ChunksExact, ChunksExactMut};
  use crate::color::{FromColor, Luma, LumaA, Rgb, Rgba, Bgr, Bgra};
  use crate::flat::{FlatSamples, SampleLayout};
  @@ -105,7 +105,7 @@ pub struct Rows<'a, P: Pixel + 'a>
  where
  <P as Pixel>::Subpixel: 'a,
  {
  - pixels: Chunks<'a, P::Subpixel>,
  + pixels: ChunksExact<'a, P::Subpixel>,
  }
  impl<'a, P: Pixel + 'a> Rows<'a, P> {
  @@ -115,7 +115,7 @@ impl<'a, P: Pixel + 'a> Rows<'a, P> {
  let row_len = (width as usize) * usize::from(<P as Pixel>::CHANNEL_COUNT);
  if row_len == 0 {
  Rows {
  - pixels: [].chunks(1),
  + pixels: [].chunks_exact(1),
  }
  } else {
  let pixels = pixels.get(..row_len*height as usize)
  @@ -123,7 +123,7 @@ impl<'a, P: Pixel + 'a> Rows<'a, P> {
  // Rows are physically present. In particular, height is smaller than `usize::MAX` as
  // all subpixels can be indexed.
  Rows {
  - pixels: pixels.chunks(row_len),
  + pixels: pixels.chunks_exact(row_len),
  }
  }
  }
  @@ -177,7 +177,7 @@ pub struct RowsMut<'a, P: Pixel + 'a>
  where
  <P as Pixel>::Subpixel: 'a,
  {
  - pixels: ChunksMut<'a, P::Subpixel>,
  + pixels: ChunksExactMut<'a, P::Subpixel>,
  }
  impl<'a, P: Pixel + 'a> RowsMut<'a, P> {
  @@ -187,7 +187,7 @@ impl<'a, P: Pixel + 'a> RowsMut<'a, P> {
  let row_len = (width as usize) * usize::from(<P as Pixel>::CHANNEL_COUNT);
  if row_len == 0 {
  RowsMut {
  - pixels: [].chunks_mut(1),
  + pixels: [].chunks_exact_mut(1),
  }
  } else {
  let pixels = pixels.get_mut(..row_len*height as usize)
  @@ -195,7 +195,7 @@ impl<'a, P: Pixel + 'a> RowsMut<'a, P> {
  // Rows are physically present. In particular, height is smaller than `usize::MAX` as
  // all subpixels can be indexed.
  RowsMut {
  - pixels: pixels.chunks_mut(row_len),
  + pixels: pixels.chunks_exact_mut(row_len),
  }
  }
  }
  