Reviewed DataModule design+docs+types

In this MR, I try to review the use of the data module and go further in simplifications for the whole code:

• Slightly streamlined the datamodule approach
• Added documentation
• Added type annotations
• Added some TODOs for further discussion

Closes #7 (closed).

TODO:

• (@dcarron) Implement/document/type hint normaliser (ensure it is used correctly through all the models; integrate on the train script) and that train CLI works!
• (@andre.anjos) Deal with import reweight_BCEWithLogitsLoss

src/ptbench/data/shenzhen/__init__.py

@@ -13,22 +13,11 @@ the daily routine using Philips DR Digital Diagnose systems.
 * Reference: [MONTGOMERY-SHENZHEN-2014]_
 * Original resolution (height x width or width x height): 3000 x 3000 or less
 * Split reference: none
-* Protocol ``default``:
-
   * Training samples: 64% of TB and healthy CXR (including labels)
   * Validation samples: 16% of TB and healthy CXR (including labels)
   * Test samples: 20% of TB and healthy CXR (including labels)
 """
 import importlib.resources
-import os
-
-from clapper.logging import setup
-
-from ...utils.rc import load_rc
-from ..loader import load_pil_baw
-
-logger = setup(__name__.split(".")[0], format="%(levelname)s: %(message)s")
-
 
 _protocols = [
     importlib.resources.files(__name__).joinpath("default.json.bz2"),
@@ -43,11 +32,3 @@ _protocols = [
     importlib.resources.files(__name__).joinpath("fold_8.json.bz2"),
     importlib.resources.files(__name__).joinpath("fold_9.json.bz2"),
 ]
-
-_datadir = load_rc().get("datadir.shenzhen", os.path.realpath(os.curdir))
-
-
-def _raw_data_loader(img_path):
-    raw_data = load_pil_baw(os.path.join(_datadir, img_path))
-
-    return raw_data