解决了在autocad中获取pline线的顶点坐标的问题，并输出至文件中-Pline-line access to the vertex coordinates

AutoCAD的教程，写的比较基础，比较适合初学者使用，书中还有一些实际应用的例子。-AutoCAD tutorial, written by more basic, more suitable for beginners, the book and some practical examples.

dxflib-3.3.4-src ，dxflib是一个用来读写DXF文件的C++库。当读DXF文件的时候,dxflib分析文件并且调用用户自己定义的函数来添加实体、层、等。-dxflib-3.3.4-src，dxflib is an opensource C++ library for reading and writing AutoCAD (R) DXF files.