C# Porting from https://sourceforge.net/projects/jsi/
Basic usage
Create a new instance: RTree.RTree tree = new RTree.RTree();
Create a rectangle: RTree.Rectangle rect = new RTree.Rectangle(1, 2, 3, 4, 5, 6);
Add a new rectangle to the RTree: tree.Add(rect, object);
Check which objects are inside the rectangle: var objects = tree.Contains(rect);
Count how many items in the RTree: var i = tree.Count;
Check which objects intersect with the rectangle: var objects = tree.Intersects(rect);
Create a point: RTree.Point point = new RTree.Point(1, 2, 3);
Get a list of rectangles close to the point with maximum distance: var objects = tree.Nearest(point, 10);