Option to show version (fixes #24)

main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"compress/gzip"
 	"crypto/tls"
+	"fmt"
 	"log"
 	"net"
 	"net/http"
@@ -30,6 +31,7 @@ type Options struct {
 	NoStats     bool             `long:"no-stats" description:"Don't print model and connection statistics"`
 	NoGUI       bool             `long:"no-gui" description:"Don't start GUI"`
 	GUIAddr     string           `long:"gui-addr" description:"GUI listen address" default:"127.0.0.1:8080" value-name:"ADDR"`
+	ShowVersion bool             `short:"v" long:"version" description:"Show version"`
 	Discovery   DiscoveryOptions `group:"Discovery Options"`
 	Advanced    AdvancedOptions  `group:"Advanced Options"`
 	Debug       DebugOptions     `group:"Debugging Options"`
@@ -71,8 +73,14 @@ var (
 func main() {
 	_, err := flags.Parse(&opts)
 	if err != nil {
+		fatalln(err)
+	}
+
+	if opts.ShowVersion {
+		fmt.Println(Version)
 		os.Exit(0)
 	}
+
 	if len(opts.Debug.TraceModel) > 0 || opts.Debug.LogSource {
 		logger = log.New(os.Stderr, "", log.Lshortfile|log.Ldate|log.Ltime|log.Lmicroseconds)
 	}