安装方法：
出现问题：error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": http://landinghub.visualstudio.com/visual-cpp-build-tools
解决方法：http://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted下载对应版本whl文件
#pip install F:\download\Twisted-17.9.0-cp36-cp36m-win_amd64.whl
try again
successfully!