add whistle to train

core/game_menu/train_selector.gd

@@ -32,6 +32,8 @@ func _set_selected_color(index: int) -> void:
 		else:
 			color_pickers[i].deselect()
 
+		AchievementManager.is_unlocked("ACH_CHANGE_TRAIN_COLOR")
+
 func _on_color_selected(selected_color_picker: TrainColorPicker) -> void:
 	for i in range(color_pickers.size()):
 		if color_pickers[i] == selected_color_picker:

core/game_menu/window_option_menu_button.gd

@@ -9,10 +9,10 @@ func _ready() -> void:
 	deselect()
 	disable()
 
-func set_option_text(text: String) -> void:
+func set_option_text(_text: String) -> void:
 	if label == null:
 		label = $%Label
-	label.text = text
+	label.text = _text
 
 func select() -> void:
 	if checkbox == null: