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/quiz_toolbar.gd

@@ -0,0 +1,25 @@
+class_name QuizToolbar
+extends Control
+## The row of quiz buttons under the top bar: reset playlist, reset points, settings
+## and sound test.
+
+signal reset_playlist_pressed
+signal reset_points_pressed
+signal settings_pressed
+signal sound_test_pressed
+
+@onready var reset_playlist_button: Button = $ResetPlaylistButton
+@onready var sound_test_button: Button = $SoundTestButton
+
+
+func _ready() -> void:
+	reset_playlist_button.pressed.connect(reset_playlist_pressed.emit)
+	$ResetPointsButton.pressed.connect(reset_points_pressed.emit)
+	$SettingsButton.pressed.connect(settings_pressed.emit)
+	sound_test_button.pressed.connect(sound_test_pressed.emit)
+
+
+## Disables the buttons that use the song list, e.g. while the server syncs it.
+func set_locked(locked: bool) -> void:
+	reset_playlist_button.disabled = locked
+	sound_test_button.disabled = locked