OpenStudio

This patch fixes the bug reported here:
http://sourceforge.net/tracker/?func=detail&aid=2884079&group_id=133018&ati
d=725735

The basic problem is that the is_subset_of? function in the Array class
uses very simple logic that may not work correctly when one of the two
arrays defines a convex polygon. This patch fixes these situations,
provided that the arrays define either vertical or horizontal surfaces
(e.g. walls or floors). In other words, it fixes most situations, but not
all possible situations. To fix all possible situations, the convert_to_2d
function in this patch would have to be generalized to create 2d
coordinates for any surface, not just vertical/horizontal surfaces.