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/SongControls.tscn

@@ -0,0 +1,48 @@
+[gd_scene format=3]
+
+[ext_resource type="Script" path="res://quiz/song_controls.gd" id="part_script"]
+
+[sub_resource type="InputEventKey" id="InputEventKey_06rl4"]
+device = -1
+alt_pressed = true
+keycode = 86
+unicode = 8249
+
+[sub_resource type="Shortcut" id="Shortcut_a7fvb"]
+events = [SubResource("InputEventKey_06rl4")]
+
+[sub_resource type="InputEventKey" id="InputEventKey_7dnqw"]
+device = -1
+alt_pressed = true
+keycode = 67
+unicode = 231
+
+[sub_resource type="Shortcut" id="Shortcut_d6fml"]
+events = [SubResource("InputEventKey_7dnqw")]
+
+[node name="SongControls" type="Control" unique_id=1640212773]
+layout_mode = 3
+offset_right = 303.0
+offset_bottom = 31.0
+mouse_filter = 2
+script = ExtResource("part_script")
+
+[node name="ShowAnswerButton" type="Button" parent="." unique_id=415388039]
+layout_mode = 0
+offset_right = 111.0
+offset_bottom = 31.0
+focus_mode = 0
+action_mode = 0
+shortcut = SubResource("Shortcut_a7fvb")
+text = "Show answer"
+
+[node name="NextButton" type="Button" parent="." unique_id=1744703488]
+layout_mode = 0
+offset_left = 128.0
+offset_right = 303.0
+offset_bottom = 31.0
+focus_mode = 0
+disabled = true
+action_mode = 0
+shortcut = SubResource("Shortcut_d6fml")
+text = "Randomize new track"