Test if the file is read-only in rm.py;
ask the user if they wants to delete it.


Add option -f for rm.py.


Add option -s for cmp.py.


Extend remove-old-files.py: add option -v/--verbose to report every removed file.


Rename remove-old-files.py to find.py. Make options more GNU find-like.


Extend find.py: add options to find files by name, extension, path.


After dropping Python 2.7: use shutil.which().