Normalize cmd arg paths

In particular, this fixes an issue on Windows where some functions
will misbehave if forward slashes are provided rather than
double backslashes.

modules/paths_internal.py

@@ -4,6 +4,10 @@ import argparse
 import os
 import sys
 import shlex
+from pathlib import Path
+
+
+normalized_filepath = lambda filepath: str(Path(filepath).resolve())
 
 commandline_args = os.environ.get('COMMANDLINE_ARGS', "")
 sys.argv += shlex.split(commandline_args)