squash merge from dev branch

vendor/gopkg.in/alecthomas/kingpin.v2/_examples/chat2/main.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"os"
+	"strings"
+
+	"gopkg.in/alecthomas/kingpin.v2"
+)
+
+var (
+	app      = kingpin.New("chat", "A command-line chat application.")
+	debug    = app.Flag("debug", "Enable debug mode.").Bool()
+	serverIP = app.Flag("server", "Server address.").Default("127.0.0.1").IP()
+
+	register     = app.Command("register", "Register a new user.")
+	registerNick = register.Arg("nick", "Nickname for user.").Required().String()
+	registerName = register.Arg("name", "Name of user.").Required().String()
+
+	post        = app.Command("post", "Post a message to a channel.")
+	postImage   = post.Flag("image", "Image to post.").File()
+	postChannel = post.Arg("channel", "Channel to post to.").Required().String()
+	postText    = post.Arg("text", "Text to post.").Strings()
+)
+
+func main() {
+	switch kingpin.MustParse(app.Parse(os.Args[1:])) {
+	// Register user
+	case register.FullCommand():
+		println(*registerNick)
+
+	// Post message
+	case post.FullCommand():
+		if *postImage != nil {
+		}
+		text := strings.Join(*postText, " ")
+		println("Post:", text)
+	}
+}