adds vendor directory

vendors dependencies in standard `vendor` directory, managed by glide

vendor/github.com/mattn/go-gtk/example/spinbutton/spinbutton.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"github.com/mattn/go-gtk/glib"
+	"github.com/mattn/go-gtk/gtk"
+	"strconv"
+)
+
+func main() {
+	gtk.Init(nil)
+	window := gtk.NewWindow(gtk.WINDOW_TOPLEVEL)
+	window.SetPosition(gtk.WIN_POS_CENTER)
+	window.SetTitle("GTK Go!")
+	window.Connect("destroy", func(ctx *glib.CallbackContext) {
+		fmt.Println("got destroy!", ctx.Data().(string))
+		gtk.MainQuit()
+	}, "foo")
+
+	//--------------------------------------------------------
+	// GtkHBox
+	//--------------------------------------------------------
+	fixed := gtk.NewFixed()
+
+	//--------------------------------------------------------
+	// GtkSpinButton
+	//--------------------------------------------------------
+	spinbutton1 := gtk.NewSpinButtonWithRange(1.0, 10.0, 1.0)
+	spinbutton1.SetDigits(3)
+	spinbutton1.Spin(gtk.SPIN_STEP_FORWARD, 7.0)
+	fixed.Put(spinbutton1, 40, 50)
+
+	spinbutton1.OnValueChanged(func() {
+		val := spinbutton1.GetValueAsInt()
+		fval := spinbutton1.GetValue()
+		fmt.Println("SpinButton changed, new value: " + strconv.Itoa(val) + " | " + strconv.FormatFloat(fval, 'f', 2, 64))
+		min, max := spinbutton1.GetRange()
+		fmt.Println("Range: " + strconv.FormatFloat(min, 'f', 2, 64) + " " + strconv.FormatFloat(max, 'f', 2, 64))
+		fmt.Println("Digits: " + strconv.Itoa(int(spinbutton1.GetDigits())))
+	})
+
+	adjustment := gtk.NewAdjustment(2.0, 1.0, 8.0, 2.0, 0.0, 0.0)
+	spinbutton2 := gtk.NewSpinButton(adjustment, 1.0, 1)
+	spinbutton2.SetRange(0.0, 20.0)
+	spinbutton2.SetValue(18.0)
+	spinbutton2.SetIncrements(2.0, 4.0)
+	fixed.Put(spinbutton2, 150, 50)
+
+	//--------------------------------------------------------
+	// Event
+	//--------------------------------------------------------
+	window.Add(fixed)
+	window.SetSizeRequest(600, 600)
+	window.ShowAll()
+	gtk.Main()
+}