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.

main/MainWindow.tscn

@@ -0,0 +1,102 @@
+[gd_scene format=3 uid="uid://xwq863o6uvsu"]
+
+[ext_resource type="PackedScene" path="res://main/TopBar.tscn" id="top_bar_scene"]
+[ext_resource type="PackedScene" path="res://quiz/Quiz.tscn" id="quiz_scene"]
+[ext_resource type="Script" uid="uid://b8f4g15cas2j2" path="res://main/main_window.gd" id="1_eu0t5"]
+[ext_resource type="PackedScene" uid="uid://bxydgil1yifps" path="res://popups/SearchPopup.tscn" id="9_5ijvr"]
+[ext_resource type="PackedScene" uid="uid://dpdem7pdxweb5" path="res://popups/SyncPopup.tscn" id="10_yxw0b"]
+[ext_resource type="PackedScene" uid="uid://bd1by80q1v27e" path="res://popups/ShortcutsPopup.tscn" id="13_8eebo"]
+[ext_resource type="PackedScene" uid="uid://btupbowehiyyu" path="res://popups/QRPopup.tscn" id="15_qr_window"]
+[ext_resource type="PackedScene" uid="uid://cp54idaudb8dp" path="res://popups/AboutPopup.tscn" id="16_about_window"]
+[ext_resource type="Theme" path="res://themes/popup_theme.tres" id="popup_theme"]
+[ext_resource type="PackedScene" uid="uid://bijh5h5yrivm3" path="res://popups/LogPopup.tscn" id="14_26rwn"]
+
+[node name="MainWindow" type="Control" unique_id=407149696]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_eu0t5")
+
+[node name="TopBar" parent="." unique_id=1734261695 instance=ExtResource("top_bar_scene")]
+
+[node name="Quiz" parent="." unique_id=1357908642 instance=ExtResource("quiz_scene")]
+
+[node name="SearchPopup" parent="." unique_id=1661250375 instance=ExtResource("9_5ijvr")]
+visible = false
+layout_mode = 1
+offset_left = 56.0
+offset_top = 96.0
+offset_right = 56.0
+offset_bottom = 96.0
+
+[node name="SyncPopup" parent="." unique_id=182499699 instance=ExtResource("10_yxw0b")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 210.0
+offset_top = 153.0
+offset_right = 210.0
+offset_bottom = 153.0
+
+[node name="QRPopup" parent="." unique_id=589733821 instance=ExtResource("15_qr_window")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 720.0
+offset_top = 153.0
+offset_right = 720.0
+offset_bottom = 153.0
+
+[node name="ShortcutsPopup" parent="." unique_id=1513416242 instance=ExtResource("13_8eebo")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 562.0
+offset_top = 160.0
+offset_right = 1262.0
+offset_bottom = 860.0
+
+[node name="StatisticsPopupPanel" type="PopupPanel" parent="." unique_id=298311407]
+theme = ExtResource("popup_theme")
+oversampling_override = 1.0
+initial_position = 2
+size = Vector2i(450, 100)
+
+[node name="Label" type="Label" parent="StatisticsPopupPanel" unique_id=548316493]
+offset_left = 4.0
+offset_top = 4.0
+offset_right = 446.0
+offset_bottom = 96.0
+text = "Statistics"
+horizontal_alignment = 1
+
+[node name="StatisticsLabel" type="Label" parent="StatisticsPopupPanel" unique_id=58226477]
+unique_name_in_owner = true
+offset_left = 4.0
+offset_top = 4.0
+offset_right = 446.0
+offset_bottom = 96.0
+text = "Total amount of soundtracks in the playlist: 9000"
+horizontal_alignment = 1
+vertical_alignment = 1
+
+[node name="AboutPopup" parent="." unique_id=141261008 instance=ExtResource("16_about_window")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 720.0
+offset_top = 153.0
+offset_right = 720.0
+offset_bottom = 153.0
+
+[node name="LogPopup" parent="." unique_id=1289881388 instance=ExtResource("14_26rwn")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 562.0
+offset_top = 132.0
+offset_right = 1262.0
+offset_bottom = 832.0