Nested Nodes Class: Manage hierarchies of MySQL database records

This class can be used to manage hierarchies of records stored in MySQL database tables.

It features:

- Works on any existing MySQL table provided that the table has three mandatory fields for the record id , position and order
- Support adding, updating and deleting nodes and the respective children
- Display the hierarchies as HTML nested lists or as breadcrumbs using HTML templates
- Supports re-ordering nodes within a given level