The util classes have been moved to infrastructure.  Added the new ZAttachObject interface for dynamic properties.
Fixed the unit test paths.  Setup the ZVisualModel to return the actual calculation objects rather than use internal calculations.
Added the new ZReferencRectangle object for special rectangles that modify other rectangles.
Updated the layout element to handle the child elements.  The layout model's prepare method now takes an iterator of child items.
Fixed a bug in the margin rectangle where the move method calculated the incorrect width.