Parse a tokens yaml instead of hardcoding the tokens

Closes #127 (closed) Extracting the entities confidence scores during prediction requires using the project tokens, this adds a --tokens argument. The yaml is then parsed to get the tokens' list.

dan/predict/__init__.py

@@ -51,6 +51,12 @@ def add_predict_parser(subcommands) -> None:
         help="Path to the output folder.",
         required=True,
     )
+    parser.add_argument(
+        "--tokens",
+        type=pathlib.Path,
+        required=True,
+        help="Path to a yaml file containing a mapping between starting tokens and end tokens. Needed for entities.",
+    )
     # Optional arguments.
     parser.add_argument(
         "--image-extension",