add NewGame panel

src/NewGamePanel.gd

@@ -0,0 +1,24 @@
+tool
+class_name NewGamePanel
+extends PopupPanel
+
+signal start_triggered(config)
+
+func _init():
+	# TODO: load config with ConfigFile
+	# https://docs.godotengine.org/en/stable/tutorials/io/saving_games.html
+	pass
+
+func _ready():
+	# TODO: load previous preferences
+	$Panel/HBoxContainer/Normal.toggle_mode = true
+	pass
+
+func _on_Cancel_pressed():
+	self.hide()
+
+func _on_Start_pressed():
+	var config = {}
+	# TODO: save config
+	emit_signal("start_triggered", config)
+	self.hide()