Initial import of tasks application

This initial import is a heavily modified version of the code I had
here, as Arse was modified for other purposes in the meantime and the
application no longer worked with it.

In addition:
 * I did not import the user management part yet,
 * task dependencies are supported in-base, but there is no interface
for that yet.

includes/t-data/item.inc.php

@@ -0,0 +1,42 @@
+<?php
+
+class Data_Item
+{
+	public $id;
+	public $name;
+	public $hasParent;
+	public $parent;
+	public $children;
+	public $depth;
+	public $lineage;
+
+	public $activeTasks;
+	public $inactiveTasks;
+
+	public function __construct( $id , $name )
+	{
+		$this->id = $id;
+		$this->name = $name;
+	}
+
+
+	public function getIdentifier( )
+	{
+		return $this->id;
+	}
+
+
+	public function getName( )
+	{
+		return $this->name;
+	}
+
+
+	public function getDepth( )
+	{
+		if ( $this->depth === null ) {
+			throw new Exception( "Method not implemented" );
+		}
+		return $this->depth;
+	}
+}