text: Title: Pad with pad mode 'wrap' does not duplicates boxes
  Body: Is there a way to use Pad (For example `iaa.PadToSquare`) with pad mode `wrap` or `reflect` that will duplicate also the boxes.
  for example:
  
  ```
  image = imageio.imread('example.jpg')
  
  bbs = BoundingBoxesOnImage([
      BoundingBox(x1=300, y1= 100, x2=600, y2=400),
      BoundingBox(x1=720, y1= 150, x2=800, y2=230),
  ], shape=image.shape)
  
  image_before = bbs.draw_on_image(image, size=2)
  ia.imshow(image_before)
  ```
  ![image](https://user-images.githubusercontent.com/44769768/97146079-e83c3280-176f-11eb-99e1-f819b9e25ed1.png)
  
  ```
  seq = iaa.Sequential([
      iaa.PadToSquare(position='right-top', pad_mode='wrap'),
  ])
  
  image_aug, bbs_aug = seq(image=image, bounding_boxes=bbs)
  image_after = bbs_aug.draw_on_image(image_aug, size=2, color=[0, 0, 255])
  ia.imshow(image_after)
  ```
  
  ![image](https://user-images.githubusercontent.com/44769768/97146223-289bb080-1770-11eb-95a4-b2e71dbb4603.png)
  
  and the boxes are missing in the newly duplicated parts of the image.
  
  Thanks a lot.
  