To customize a core source file, copy it to this directory matching the
directory structure of the original file.

For example, to make custom changes to

ClicShopping/OM/Session/File.php

copy the complete file to

ClicShopping/Custom/Session/File.php

and perform your changes to this new file.

## NOTES ##

Although the custom class is copied to a Custom directory, it must retain the
original includes namespace.

Due to this, copied classes cannot extend the original class in the includes
namespace.
