closed #2494: Fix bug when two line is incident, the Point::isSegmentIntersect() may return wrong result
closed #2494: Fix some typo
closed #2494: add isLineOverlap, isLineParallel, isSegmentOverlap method to Point.
Merge pull request #3470 from boyu0/iss2494_Point_isSegmentIntersect_bug

closed #2494: Fix bug when two line is incident, the Point::isSegmentIntersect() may return wrong result