Make square centre-padding a model transform

This MR fixes issues #23 (closed) and #39 (closed), by:

• Removing centre-cropping from all databases raw-data loaders
• Creating a SquareCenterPad transform that operates on tensors
• Adding that transform to all relevant models (Pasa, Alexnet, Densenet)

src/mednet/config/data/hivtb/datamodule.py

@@ -12,7 +12,7 @@ import os
 
 import PIL.Image
 
-from torchvision.transforms.functional import center_crop, to_tensor
+from torchvision.transforms.functional import to_tensor
 
 from ....data.datamodule import CachingDataModule
 from ....data.image_utils import remove_black_borders
@@ -58,7 +58,6 @@ class RawDataLoader(_BaseRawDataLoader):
         )
         image = remove_black_borders(image)
         tensor = to_tensor(image)
-        tensor = center_crop(tensor, min(*tensor.shape[1:]))
 
         # use the code below to view generated images
         # from torchvision.transforms.functional import to_pil_image