Additional cleanup per mypy

- Add Callable type to hasher (should realy be more specific...)
- Add type hint to COLUMNS in qtlib/table.py
- Use Qt.ItemFlag.ItemIsEnabled instead of Qt.itemIsEnabled in qtlib/table.py

core/fs.py

@@ -13,6 +13,16 @@
 
 import os
 
+from math import floor
+import logging
+import sqlite3
+from threading import Lock
+from typing import Any, AnyStr, Union, Callable
+
+from pathlib import Path
+from hscommon.util import nonone, get_file_ext
+
+hasher: Callable
 try:
     import xxhash
 
@@ -22,15 +32,6 @@ except ImportError:
 
     hasher = hashlib.md5
 
-from math import floor
-import logging
-import sqlite3
-from threading import Lock
-from typing import Any, AnyStr, Union
-
-from pathlib import Path
-from hscommon.util import nonone, get_file_ext
-
 __all__ = [
     "File",
     "Folder",