Intersection providing more than 1 body is not considering all bodies

Whenever you call the ``body.intersect()`` method, if your bodies intersect in 2 different locations, the user only gets back one of them instead of all the intersections... This can be "fixed" but updating the design "in-place" but we should really check all the affected bodies and update the ``Design`` object accordingly.

Initially reported by @NMLDNV