R-tree
R*-Tree in C++, not template.
This is modified based on Dustin Spicuzza's code, which is wroten using generics, that may offer a more easy-to-use option. Thanks to his work! Since for my specific project no metaprogramming needed, so I just removed it.
Basicly I adopted Spicuzza's Insert method, rewrite Delete and Query method, and added FIFO feature for leaf nodes, to keep leaf amount constant. Thus this is not a dedicated storage model.
Based on Guttman: R-trees: A Dynamic Index Structure for Spatial Searching, and Beckmann: The R*-tree: An Efficient and Robust Access Method for Points and Rectangles