Plottable Online Class: Store online users statistics in a MySQL database

This class uses a database table to keep track of several statistics about the users online of a site.

Features:

- Uses a MySql as backend
- Determines a new visitor based on IP address and session id
- Supports different modes of detect a new visitor
- Keep track of the maximum number of users that were online since it is started
- Creates the statistics table on demand. There is no need to use phpmyadmin or other program to initialize the database table.
- The class methods are completely documented within the class code comments