Address change requests in first round of PR reviews.

Pending:

- Move model install calls into model manager and create passthrus in invocation_context.
- Consider splitting load_model_from_url() into a call to get the path and a call to load the path.

invokeai/backend/util/util.py

@@ -1,6 +1,8 @@
 import base64
 import io
 import os
+import re
+import unicodedata
 import warnings
 from pathlib import Path
 
@@ -12,6 +14,25 @@ from transformers import logging as transformers_logging
 GIG = 1073741824
 
 
+def slugify(value: str, allow_unicode: bool = False) -> str:
+    """
+    Convert to ASCII if 'allow_unicode' is False. Convert spaces or repeated
+    dashes to single dashes. Remove characters that aren't alphanumerics,
+    underscores, or hyphens. Convert to lowercase. Also strip leading and
+    trailing whitespace, dashes, and underscores.
+
+    Adapted from Django: https://github.com/django/django/blob/main/django/utils/text.py
+    """
+    value = str(value)
+    if allow_unicode:
+        value = unicodedata.normalize("NFKC", value)
+    else:
+        value = unicodedata.normalize("NFKD", value).encode("ascii", "ignore").decode("ascii")
+    value = re.sub(r"[/]", "_", value.lower())
+    value = re.sub(r"[^\w\s-]", "", value.lower())
+    return re.sub(r"[-\s]+", "-", value).strip("-_")
+
+
 def directory_size(directory: Path) -> int:
     """
     Return the aggregate size of all files in a directory (bytes).