MG's TreeView: Display list of elements of nested menus

To use the Tree View Control, just instance a new object with a string that
stands for the title:

$tree = new TreeView("The Title");

or initialize with an array:

$array = array("Node 1", array("Subnode 1", "Subnode 2"), "Node 2");
$tree = new TreeView("TheTitle");

to add later a node, just

$tree->AddNode($array_with_node);

to remove by querying the nodelist:

$tree->RemoveNode("Node 1");