public final void addVertex(final int lon, final int lat) {
        points.add(new Point(lon, lat));
    }
intersect2D_2Segments(): find the 2D intersection of 2 finite segments

@param s1p0 start point of segment 1
@param s1p1 end point of segment 1
@param s2p0 start point of segment 2
@param s2p1 end point of segment 2
@return 0=disjoint (no intersect)
1=intersect in unique point I0
2=overlap in segment from I0 to I1
main/src/main/java/cgeo/geocaching/brouter/core/OsmNogoPolygon.java