Create Session class, Database_Objects class
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Highlights:
- Created Session object to maintain seperation between public and admin area
- Added initialize.php to add reuire_once() files in one place
- Split header and footer into seperate sections, and added into layouts folder
- Created Database_Objects class to hold all common databse methods that should be shared among others
- User class is now an extension of Database_Objects
- Late Static Binding (Use of static:: and get_called_class())

Files:
- new file:   includes/database_objects.php
- modified:   includes/functions.php
- new file:   includes/initialize.php
- new file:   includes/session.php
- modified:   includes/user.php
- new file:   public/admin/index.php
- new file:   public/admin/login.php
- modified:   public/index.php
- new file:   public/layouts/admin_footer.php
- new file:   public/layouts/admin_header.php
- new file:   public/layouts/footer.php
- new file:   public/layouts/header.php
- modified:   public/stylesheets/main.css