initial stab at disk 3 area.

Also made hidden items visible by default since they will become hidden when the game starts anyway. This way they are visible in the editor.

hidden_spike.tscn

@@ -6,7 +6,7 @@
 [sub_resource type="RectangleShape2D" id="RectangleShape2D_xfwl5"]
 size = Vector2(15, 7.5)
 
-[node name="HiddenSpike" type="Node2D" unique_id=1739014101]
+[node name="HiddenSpike" type="Node2D" unique_id=1739014101 groups=["Hidden"]]
 visible = false
 script = ExtResource("1_k2eht")