iOS: Fix major memory leaks when destroying widgets and windows. More surely needs to be done regardig this, iOS doesn't destroy subviews as expected when the parent is removed. I was expecting it to bring the reference counts to 0 and starts destroying subviews... so I had to do this manually. Boxes, ScrollBoxes, Spinbuttons and Comboboxes all now destroy their subviews. Probably will need to do the same for splitbar, notebooks and possibly others. However this stops the memory leak in Interface Builder when recreating the interface. Also need to figure out why the reference count is lower for DWButtons.