#3 boxes need stacking order

[Brian Smith]

The text boxes need assignable stacking order. If multiple text boxes overlap, the appear to stack in the order that the boxes were added. However, this order may change the next time that the whiteboard is loaded. Also, it would be very nice to add "send to bottom", "send back", "bring forward" and "bring to top" functions from a right-clickable menu. By assigning a discrete number (internal) to the stacking order, this will prevent reloads from reordering the boxes.