Franklin's Point Inclusion in Polygon (PNPOLY) Algorithm

This Demonstration implements Franklin's point inclusion in polygon (PNPOLY) algorithm [1] that tests whether a point is inside a polygon (convex or concave). The idea, based on Jordan's curve theorem, is to count how many times a ray from the test point crosses an edge of the polygon. At each crossing, the status changes from inside to outside or vice versa.