go cli

• go build [-o output] [-i] [build flags] [packages], compiles the packages named
  • for single main package, build writes the resulting executable to an output file named after the first source file
• go env prints environment info
• go fmt [packages] prints names of files that are modified
• go get [packages] downloads packages named by import paths and their dependencies
• `go install [packages] compiles and installs packages