Dialog box starts hidden

It was visible until the first dialog ended, so a scene entered without a
running scenario (a loaded save on an RPG map, the return from a battle)
showed an empty box that nothing closed. SetDialogQueueAndRun shows it.

scenes/ui/dialog_box.tscn

@@ -11,6 +11,7 @@ anchor_right = 1.0
 anchor_bottom = 1.0
 grow_horizontal = 2
 grow_vertical = 2
+visible = false
 script = ExtResource("1_dialogbox")
 answerBoxScene = ExtResource("2_answerbox")