golang 安装常用工具

配置环境变量 GOPATH，下载后的工具源代码和编译后包会安装到GOPATH的第一个配置路径的src, bin, pkg目录下；配置环境变量 GOPATH/bin；配置环境变量 GIT；分别执行下面命令：

go get -u -v github.com/nsf/gocodego get -u -v github.com/rogpeppe/godefgo get -u -v github.com/golang/lint/golintgo get -u -v github.com/lukehoban/go-outlinego get -u -v sourcegraph.com/sqs/goreturnsgo get -u -v golang.org/x/tools/cmd/gorenamego get -u -v github.com/tpng/gopkgsgo get -u -v github.com/newhook/go-symbolsgo get -u -v golang.org/x/tools/cmd/guru