TTF字体裁减工具。它在开源的sfnttool上修改而来，增加了以文件的方式来配置需要提取出来的字体内容。

- 使用示例 `java -jar sfnttool.jar -f a.txt Alibaba-PuHuiTi-Regular.ttf out.ttf` - 帮助文档 Subset [-?|-h|-help] [-b] [-s string] fontfile outfile Prototype font subsetter -?,-help print this help information -s,-string String to subset -f,-file file String to subset -b,-bench Benchmark (run 10000 iterations) -h,-hints Strip hints -w,-woff Output WOFF format -e,-eot Output EOT format -x,-mtx Enable Microtype Express compression for EOT format