Preference Manager is a class to handle user preferences in a web application,
looking them up in a table using a combination of their userid, and the
preference name to get a value, and (optionally) returning a default value for
the preference if no value could be found for that user.

It is designed to be used alongside the PEAR Auth class, but can be used with
anything that allows you to obtain the user's id - including your own code.