text: Title: Adding intermediate information in a custom augmentation
  Body: Apologies in advance if a version of this has been asked before, but I wasn't able to find any info. I have a custom augmentation that takes an image and a bounding box, expands the bbox randomly within limits and then crops. If i want to also access the expanded bbox that was used, how can I get that information from the output? For reference, here's the basic code skeleton. Assume `crop`, `expand` and `jitter_bbox` functions exist, and that cases where expansions protrude beyond image boundaries are handled:
  
  ```
  class RandomExpansion(A.DualTransform):
      def __init__(self, 
                   expansion_limits=[0.0, 0.5],
                   always_apply=False, 
                   p=0.5,
                   ):
  
          super(RandomExpansion, self).__init__(always_apply, p)
          self.expansion_limits = expansion_limits
  
      def apply(self, np_img, x_min, x_max, y_min, y_max, **params):
          h, w = np_img.shape[:2]
          exp_bbox = np.array([x_min, y_min, x_max, y_max])
          return crop(np_img, exp_bbox)
          
      def apply_to_bbox(self, bbox, **params):
          x_min = np.clip(bbox[0], 0.0, 1.0)
          y_min = np.clip(bbox[1], 0.0, 1.0)
          x_max = np.clip(bbox[2], 0.0, 1.0)
          y_max = np.clip(bbox[3], 0.0, 1.0)
  
          return (x_min, y_min, x_max, y_max)
  
      @property
      def targets_as_params(self):
          return ["image", "bboxes"]
      
      def get_params_dependent_on_targets(self, params):
          h, w = params["image"].shape[:2]
          norm_bbox = params["bboxes"][0]
          bbox = denormalize_bbox(norm_bbox, h, w)[:4]
  
          # jitter the bbox randomly
          bbox = jitter_bbox(bbox)
  
          # expand randomly
          exp_factor = np.random.uniform(
              self.expansion_limits[0], self.expansion_limits[1]
          )
          exp_bbox = expand(bbox, exp_factor)
          ex1, ey1, ex2, ey2 = exp_bbox
  
          return {
              "x_min": ex1,
              "y_min": ey1,
              "x_max": ex2,
              "y_max": ey2,
          }
  ```
  
  Ideally, after calling wrapping this with `A.Compose`,  I'd do something like `out = tfm(image=<np_img>, bboxes=<bbox>)` and would want `out` to also contain the `exp_bbox` being referenced above. Is there a way to do this?
  
  