Includes the following classes:
* `BasicAuth' which depends on web server "Basic" authentication
* Cookie based classes `SessionCookieAuth' and `StatelessCookieAuth'
* Hidden field based classes `SessionHiddenAuth' and
sending passwords as clear text.
Class constructor must be called BEFORE HTTP headers are output.
All Authentication object constructors either return (possibly having
output cookie headers) or exit (having output a login form, or error
cgiauth.py functions as a test if invoked as a CGI script, and as a
password file creator if invoked from the command line.
Developed/tested under Python 2.5
TODO: Brief introduction on what you do with files - including link to relevant help section.