Extension:Graphical Category Browser

Why is this extension necessary?
Showing the interconnection of categories as a graph enhances navigability of the site.

What this extension does

 * A special page "Graphical Categories Browser" is added.
 * A graph is added on top of each category page showing the relationships to other categories.

Images are file cached. Cache control to match html and image output is supplied.

Installation
To change the design you may override entries in the following array:
 * Install Graphviz - Graph Visualization Software.
 * Download script and copy to extensions.
 * Correct $xyDotPath and $xyCategoriesCache to Your needs.
 * Create directory images/xyGraphvizCache
 * Add the following line to LocalSettings.php