Enable camera smoothing

A rumble effect appears, need to be fixed.

Game.tscn

@@ -64,3 +64,4 @@ tile_data = PoolIntArray( 0, 1, 0, 1, 1, 0, 2, 1, 0, 3, 1, 0, 4, 1, 0, 5, 1, 0,
 [node name="MainCamera" type="Camera2D" parent="."]
 position = Vector2( 352, 736 )
 current = true
+smoothing_enabled = true