Sort the scripts and scenes into folders

main/ holds the main window and top bar, quiz/ the quiz and its parts,
player/ the music player, popups/ every popup and what they share, data/ the
songs, players, playlist and settings, server/ the MusicServer client,
common/ the list row and GameLog, and themes/ the themes and style boxes.

quiz/now_playing.gd

@@ -0,0 +1,10 @@
+class_name NowPlaying
+extends VBoxContainer
+## The soundtrack and song that are playing, in large text at the top of the quiz.
+
+
+## Shows [param soundtrack_title] and [param song_title]. The playlist hides them as
+## question marks until the answer is shown.
+func show_song(soundtrack_title: String, song_title: String) -> void:
+	$SoundtrackLabel.text = soundtrack_title
+	$SongLabel.text = song_title