说明：  求解二进制stl文件的体积及表面积；总体积是对所有的四面体的体积进行求和，总面积是对所有的三角面片进行求和
(Solving the volume and surface area of binary STL files. The total volume is the sum of the volumes of all tetrahedrons, and the total area is the sum of all triangles.)