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.

popups/QRPopup.tscn

@@ -0,0 +1,56 @@
+[gd_scene format=3 uid="uid://btupbowehiyyu"]
+
+[ext_resource type="Script" uid="uid://bsa6xg5xos6h7" path="res://popups/qr_popup.gd" id="1_qr_script"]
+[ext_resource type="Script" uid="uid://dynulhnyq5hpq" path="res://addons/kenyoni/qr_code/qr_code_rect.gd" id="2_jpsxt"]
+[ext_resource type="Theme" path="res://themes/popup_theme.tres" id="popup_theme"]
+
+[node name="QRPopup" type="Control" unique_id=1996957585 node_paths=PackedStringArray("panel")]
+theme = ExtResource("popup_theme")
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_qr_script")
+panel = NodePath("QRPanel")
+
+[node name="QRPanel" type="Panel" parent="." unique_id=1021365843]
+unique_name_in_owner = true
+layout_mode = 0
+offset_right = 450.0
+offset_bottom = 520.0
+
+[node name="QRCodeRect" type="TextureRect" parent="QRPanel" unique_id=1054378438]
+unique_name_in_owner = true
+layout_mode = 0
+offset_left = 20.0
+offset_top = 20.0
+offset_right = 430.0
+offset_bottom = 430.0
+script = ExtResource("2_jpsxt")
+auto_update = true
+mode = 4
+error_correction = 3
+use_eci = true
+eci_value = 26
+data = ""
+auto_version = true
+auto_mask_pattern = true
+light_module_color = Color(1, 1, 1, 1)
+dark_module_color = Color(0, 0, 0, 1)
+auto_module_size = false
+module_size = 8
+quiet_zone_size = 4
+metadata/_custom_type_script = "uid://dynulhnyq5hpq"
+
+[node name="URLLabel" type="Label" parent="QRPanel" unique_id=230761497]
+unique_name_in_owner = true
+layout_mode = 0
+offset_left = 20.0
+offset_top = 450.0
+offset_right = 430.0
+offset_bottom = 490.0
+text = "URL"
+horizontal_alignment = 1
+vertical_alignment = 1