message: Derive Clone for iterators
diff: @@ -15,6 +15,7 @@ use crate::traits::{EncodableLayout, Pixel};
  use crate::utils::expand_packed;
  /// Iterate over pixel refs.
  +#[derive(Clone)]
  pub struct Pixels<'a, P: Pixel + 'a>
  where
  P::Subpixel: 'a,
  @@ -99,6 +100,7 @@ where
  /// This iterator is created with [`ImageBuffer::rows`]. See its document for details.
  ///
  /// [`ImageBuffer::rows`]: ../struct.ImageBuffer.html#method.rows
  +#[derive(Clone)]
  pub struct Rows<'a, P: Pixel + 'a>
  where
  <P as Pixel>::Subpixel: 'a,
  @@ -239,6 +241,7 @@ where
  }
  /// Enumerate the pixels of an image.
  +#[derive(Clone)]
  pub struct EnumeratePixels<'a, P: Pixel + 'a>
  where
  <P as Pixel>::Subpixel: 'a,
  @@ -277,6 +280,7 @@ where
  }
  /// Enumerate the rows of an image.
  +#[derive(Clone)]
  pub struct EnumerateRows<'a, P: Pixel + 'a>
  where
  <P as Pixel>::Subpixel: 'a,
  