Extend "os" package with Executable and ExecutableFolder

 This Go library implements functions for discovering the current
 executable and folder to re-invoke the currently running program.
 This can be useful for upgrading the current executable or finding
 resources located relative to the executable file. Both working
 directory and the os.Args[0] value are arbitrary and cannot be
 relied on; os.Args[0] can be "faked"
 .
 These methods are available in the "os" package from Go 1.8 and later.