Make parts face right directions

When I finally got this to display in-game (by pasting it into another
vehicle's slot, Cata refuses to let me add a new vehicle entry), this
looked like Vincent Van Goh designed it. D'oh.  Anyway, now everything
faces the right way.  Also changed the single third-row seat to an
aisle, because I felt bad for the poor soldier who got wedged in the
tiny space in back; also now someone in the vehicle could more easily
walk back to get gear out of the trunks or reload the rear turret.