Log through a GameLog autoload instead of print()

GameLog.debug() prints only in debug builds, and GameLog.warning() reports
problems such as unexpected server data or failed downloads.

song_loader.gd

@@ -20,7 +20,7 @@ var retry_seconds: float = 5.0
 ## Loads the songs already in the server playlist, then starts preloading new ones.
 ## Preloading waits for the list, because loading the list clears the playlist.
 func load_song_list() -> void:
-	print("load_song_list")
+	GameLog.debug("load_song_list")
 	var song_list_fetched: Callable = func song_list_fetched(data) -> void:
 		Playlist.clear_song_list()
 		if typeof(data) == TYPE_ARRAY:
@@ -33,7 +33,7 @@ func load_song_list() -> void:
 				new_song_object.has_played = true
 				Playlist.add_to_playlist(new_song_object)
 		elif data != null:
-			print("Unexpected data")
+			GameLog.warning("Unexpected data")
 		Playlist.update_last_played_song()
 		song_list_loaded.emit()
 		fetch_song_if_idle()
@@ -42,7 +42,7 @@ func load_song_list() -> void:
 
 ## Starts downloading one more song, which keeps downloading until the cache is full.
 func fetch_song() -> void:
-	print("fetch_song")
+	GameLog.debug("fetch_song")
 	Playlist.is_song_downloading = true
 	_download_random_song(SongObject.new())
 
@@ -64,7 +64,7 @@ func fill_cache() -> void:
 # the server and the game keep the same songs in their playlists.
 func _download_random_song(new_song_object: SongObject) -> void:
 	var song_downloaded: Callable = func song_downloaded(body: PackedByteArray) -> void:
-		print("song_downloaded")
+		GameLog.debug("song_downloaded")
 		var sound: AudioStream = AudioStreamMP3.new()
 		sound.data = body
 		new_song_object.song = sound
@@ -80,11 +80,11 @@ func _add_song_to_queue(new_song_object: SongObject) -> void:
 
 func _fetch_song_info(new_song_object: SongObject) -> void:
 	var song_info_fetched: Callable = func song_info_fetched(data_received: Dictionary) -> void:
-		print("song_info_fetched")
+		GameLog.debug("song_info_fetched")
 		new_song_object.song_number = data_received.SongNo
 		new_song_object.soundtrack_title = data_received.Soundtrack
 		new_song_object.song_title = data_received.Song
-		print("new_song_object: ", new_song_object.to_string())
+		GameLog.debug("new_song_object: ", new_song_object.to_string())
 		Playlist.add_to_playlist(new_song_object)
 		if Playlist.should_preload_more_songs():
 			fetch_song()
@@ -96,5 +96,5 @@ func _fetch_song_info(new_song_object: SongObject) -> void:
 
 
 func _retry_later(step: Callable) -> void:
-	print("Song download failed, retrying in %s seconds" % retry_seconds)
+	GameLog.warning("Song download failed, retrying in %s seconds" % retry_seconds)
 	get_tree().create_timer(retry_seconds).timeout.connect(step)