Cleanup, bugfixes. Added access control on files and API.

cista/util/filename.py

@@ -1,7 +1,9 @@
-from pathvalidate import sanitize_filepath
 import unicodedata
 from pathlib import PurePosixPath
 
+from pathvalidate import sanitize_filepath
+
+
 def sanitize(filename: str) -> str:
     filename = unicodedata.normalize("NFC", filename)
     # UNIX filenames can contain backslashes but for compatibility we replace them with dashes