quarterpanel proof of concept and example design (car)

As suggested in the comments, added quarterpanels.  A quarterpanel is an
obstacle, but does not block vision.  It has 250 durability, or
one-quarter of a board.  Also, as an experiment, turned all boards on
the "car" into quarterpanels, added quarterpanels over wheels, and moved
headlights to the top two corners of the vehicle, eg. where the wheels
are.  I think this makes a more realistic looking car, putting it up so
people can comment.