Member VisiLibity::Environment::compute_partition_cells (std::vector< Line_Segment > partition_inducing_segments, double epsilon=0.0): finish this
Member VisiLibity::Environment::shortest_path (const Point &start, const Point &finish, const Visibility_Graph &visibility_graph, double epsilon=0.0): return not just one, but all shortest paths (w/in epsilon), e.g., returning a std::vector<Polyline>)
Class VisiLibity::Visibility_Graph: Add method to prune edges for faster shortest path calculation, e.g., exclude concave vertices and only include tangent edges as described in ``Robot Motion Planning" (Ch. 4 Sec. 1) by J.C. Latombe.