add basic tray functionality

enable with `make TRAY=on ...`. Cross compilation apparently should work
from linux to linux & windows.

tray.go

@@ -0,0 +1,94 @@
+// +build tray
+
+package main
+
+import (
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/getlantern/systray"
+)
+
+var TRAY = true
+
+func RunTray() {
+	systray.Run(onReady, onExit)
+}
+
+func onExit() {
+	if RUNNING {
+		QUIT = true
+		RESTART <- true
+	}
+	os.Remove(SOCK)
+}
+
+func onReady() {
+	icon, err := localFS.ReadFile("web/favicon.ico")
+	if err != nil {
+		log.Fatalf("Failed to load favicon: %v", err)
+	}
+
+	systray.SetIcon(icon)
+	systray.SetTitle("jfa-go")
+	mStart := systray.AddMenuItem("Start", "Start jfa-go")
+	mStop := systray.AddMenuItem("Stop", "Stop jfa-go")
+	mRestart := systray.AddMenuItem("Restart", "Restart jfa-go")
+	mQuit := systray.AddMenuItem("Quit", "Quit jfa-go")
+	mOnBoot := systray.AddMenuItemCheckbox("Run on login", "Run jfa-go on user login.", false)
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+	go func() {
+		<-c
+		systray.Quit()
+		os.Exit(1)
+	}()
+	defer func() {
+		systray.Quit()
+	}()
+
+	RESTART = make(chan bool, 1)
+	go start(false, true)
+	mStart.Disable()
+	mStop.Enable()
+	mRestart.Enable()
+	for {
+		select {
+		case <-mStart.ClickedCh:
+			if !RUNNING {
+				go start(false, false)
+				mStart.Disable()
+				mStop.Enable()
+				mRestart.Enable()
+			}
+		case <-mStop.ClickedCh:
+			if RUNNING {
+				RESTART <- true
+				mStop.Disable()
+				mStart.Enable()
+				mRestart.Disable()
+			}
+		case <-mRestart.ClickedCh:
+			if RUNNING {
+				RESTART <- true
+				mStop.Disable()
+				mStart.Enable()
+				mRestart.Disable()
+				for {
+					if !RUNNING {
+						break
+					}
+				}
+				go start(false, false)
+				mStart.Disable()
+				mStop.Enable()
+				mRestart.Enable()
+			}
+		case <-mQuit.ClickedCh:
+			systray.Quit()
+		}
+	}
+}