remove open-golang dependency

src/platform/open_win.go

@@ -0,0 +1,12 @@
+// +build windows
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+func open(input string) *exec.Cmd {
+	rundll32 := filepath.Join(os.Getenv("SYSTEMROOT"), "System32", "rundll32.exe")
+	return exec.Command(rundll32, "url.dll,FileProtocolHandler", input)
+}