code: public boolean overlaps(BoundingBox o, double cutoff) {
  		if (this==o) return true;
  		// x dimension
  		if (!areOverlapping(xmin,xmax,o.xmin,o.xmax,cutoff)) {
  			return false;
  		}
  		// y dimension
  		if (!areOverlapping(ymin,ymax,o.ymin,o.ymax,cutoff)) {
  			return false;
  		}
  		// z dimension
  		if (!areOverlapping(zmin,zmax,o.zmin,o.zmax,cutoff)) {
  			return false;
  		}
  		return true;
  	}
docs: Returns true if this bounding box overlaps given one, i.e. they are within
  one cutoff distance in one of their 3 dimensions.
  @param cutoff
  @return