Quadtree implementation from https://github.com/kpully/quadtree extended with nearest neighbor search.
- finds node corresponding to point and local nn (inside node)
- draws a box around the point (size dep on distance to local nn)
- rectangle collision gives all node canditates for global nn.
The quadtree and node class are used for an RRT program made for a coursera Modern Robotics(course 4, week 2) assignment link.