createSquare method
Creates a CW square around a point
Implementation
void createSquare(Coordinate p) {
segList.addPt(new Coordinate(p.x + distance, p.y + distance));
segList.addPt(new Coordinate(p.x + distance, p.y - distance));
segList.addPt(new Coordinate(p.x - distance, p.y - distance));
segList.addPt(new Coordinate(p.x - distance, p.y + distance));
segList.closeRing();
}