从文件读取四叉树结点，按照morton码对四叉树进行编码-Read from the file quadtree node, in accordance with morton yards on the quad-tree coding

一个对简单的XML文件进行的程序，里面包含了对文件的读写和多叉树递归遍历。-A simple XML file for the procedure, which contains the document to read and write and many Recursive quadtree traversal.