beta-1.4/persistence-implementation (#3)

Reviewed-on: #3

Entities/Map Objects/Gates/Spike Gate/Scripts/spike_gate.gd

@@ -1,5 +1,7 @@
 extends StaticBody2D
 
+signal Opened
+
 @onready var sprite: AnimatedSprite2D = $AnimatedSprite2D
 @onready var collision_shape_2d: CollisionShape2D = $CollisionShape2D
 
@@ -15,3 +17,5 @@ func OpenGate() -> void:
 	
 	collision_shape_2d.set_deferred("disabled", true)
 	sprite.play("open")
+	
+	Opened.emit()