Fixed utils.boxCircle, changed box debug display

boxCircle: First of all, cleaned up a bit. We don't actually need
four anchor points, only two. Fixed a howler of a bug that was
using the 'filled' parameter incorrectly, boxing only outlines of
filled circles and all of unfilled ones.

boxDebug: Changed from the old display to an alpha-valued filled
box. This makes it much easier to get a handle on the shapes of
the boxes.