Remove unused code

- The old character select scene, which was never shown but loaded
  every character image at startup
- Unused SyncResponse and ProgressResponse classes
- Playlist.set_last_played_answered and select/local-loading code in
  the new character select, none of which were called
- Settings.delete_player_children, identical to delete_children
- An unused variable holding a local file path

MainWindow.gd

@@ -109,9 +109,6 @@ var player_container: VBoxContainer = $Players/VBoxContainer
 @onready
 var players_list_container: VBoxContainer = $Players/VBoxContainer/ScrollContainer/PlayersListVBoxContainer
 
-@onready
-var character_select: Control = $CharacterSelect
-
 @onready
 var new_character_select: Control = %NewCharacterSelect
 
@@ -171,7 +168,6 @@ func _ready() -> void:
 	reset_playlist_button.pressed.connect(reset_playlist)
 	reset_points_button.pressed.connect(reset_points)
 	
-	character_select.connect("character_selected", _on_character_selected)
 	new_character_select.connect("new_new_character_selected", _on_new_character_selected)
 	new_player_name_field.connect("enter_key_pressed", add_player)
 	music_player_container.connect("play_next_song", play_next_song)
@@ -457,7 +453,7 @@ func add_player() -> void:
 
 func load_players() -> void:
 	print("load_players")
-	Settings.delete_player_children(players_list_container)
+	Settings.delete_children(players_list_container)
 	var counter: int = 0
 	for player_object: PlayerObject in Settings.player_array:
 		print(player_object.player_name)
@@ -512,11 +508,6 @@ func _on_player_change_character_clicked(new_player: Player, player_name: String
 	print("Change character for: " + player_name)
 	new_character_select.show_grid(player_name)
 
-func _on_character_selected(file_name: String) -> void:
-	print("_on_character_selected")
-	character_select.visible = false
-	current_player.character_selected(file_name)
-
 func _on_new_character_selected(character_texture: ImageTexture) -> void:
 	print("_on_new_character_selected")
 	current_player.new_character_selected(character_texture)