简化数据模型 jianhuachengxu

代码说明：

  简化数据模型、减少数据处理时间、提高成型效率。算法无需建立三角面片之间的拓扑关系，可直接进行切片分层，切平面与网格面片所得的交线段也无需排序，节省了生成轮廓线时对交线段重新排序所需的时间，提高了分层处理的效率。(Simplify the data model, and to reduce the data processing time and improve the molding efficiency. Algorithm without establishing the topological relationships between the triangular dough piece, can be directly slice layered tangential plane with the grid cross-segment of the dough piece obtained without sorting, save when the contour line is generated on the cross segment reordering the time required, improve the efficiency of the hierarchical processing.)