Original code by Martin Blais (GPLv2 Copyright Martin Blais 2001-2008)
Add license information and GPL modification notice.
Demote license and modification notice to H2
Conversion for Python 3.3.2: use argparse, print needs parenthesis.
Update __doc__.
Add compatibility notice.
Add class to contain default values as "constants"
Add option to remove the files
Don't create the file if the current directory has a subdirectory (it will be retained because the subdir either has files, or a keep file will be created in an empty subdir)
Add a dry-run option
Add a summary of what the script did.
Add some error checking to make sure the specified path(s) are actually directories
Add the option to ignore one or more directory names.
Add verbose options to see what is happening