Move static group assignation to group editor

Instead of using _ready callback to assign group.

Player.gd

@@ -40,8 +40,6 @@ export var turn_left_action:String
 export var turn_right_action:String
 
 func _ready():
-	add_to_group("players")
-
 	assert(turn_left_action)
 	assert(turn_right_action)
 

Player.tscn

@@ -7,7 +7,9 @@
 [sub_resource type="RectangleShape2D" id=1]
 extents = Vector2( 16, 16 )
 
-[node name="Player" type="Area2D"]
+[node name="Player" type="Area2D" groups=[
+"players",
+]]
 script = ExtResource( 1 )
 
 [node name="Sprite" type="Sprite" parent="."]

Spawner.gd

@@ -1,4 +1,4 @@
 extends Sprite
 
 func _ready():
-	add_to_group("spawn")
+	pass

Spawner.tscn

@@ -3,6 +3,8 @@
 [ext_resource path="res://Spawner.gd" type="Script" id=1]
 [ext_resource path="res://Resources/Images/spawn.png" type="Texture" id=2]
 
-[node name="Spawn" type="Sprite"]
+[node name="Spawn" type="Sprite" groups=[
+"spawn",
+]]
 texture = ExtResource( 2 )
 script = ExtResource( 1 )