Name popups *Popup and give scripts, scenes and classes matching names

Every popup is now called *Popup instead of *Window in its file, root node,
node name, class and variable, and PopupWindow becomes BasePopup. Player is
PlayerRow, SongListObject is SongRow and Character is CharacterCard. Script
files are snake_case and scene files PascalCase, each matching its class or
root node, and LightGrayTheme.tres is light_gray_theme.tres.

tests/integration/test_layout_unchanged.gd

@@ -10,33 +10,53 @@ extends GdUnitTestSuite
 
 const BASELINE_PATH: String = "res://tests/data/layout_baseline.json"
 
-## Nodes that moved from the main window into the Quiz scene, by their old name.
-const QUIZ_NODES: Array[String] = [
-	"Open", "FileDialog", "MusicListPanel", "DebugLabel", "SettingsWindow",
-	"NewCharacterSelect", "WinnerWindow",
-]
-
-## Nodes that moved into the Quiz scene under another path: old name to new path in
-## the quiz.
-const RENAMED_QUIZ_NODES: Dictionary = {
-	"Players": "PlayersPanel",
-	"ScrollContainer": "InspirationList",
-	"VBoxContainer": "NowPlaying",
-	"MusicPlayer": "MusicPlayer/PlayerBar",
-	"RepeatSongCheckButton": "MusicPlayer/RepeatSongCheckButton",
-	"ResetPlaylistButton": "QuizToolbar/ResetPlaylistButton",
-	"ResetPointsButton": "QuizToolbar/ResetPointsButton",
-	"SettingsButton": "QuizToolbar/SettingsButton",
-	"SoundTestButton": "QuizToolbar/SoundTestButton",
-	"ShowAnswerButton": "SongControls/ShowAnswerButton",
-	"NextButton": "SongControls/NextButton",
+## Where each node of the old main window lives now: its old name, and the path that
+## replaces it. Nodes that are not listed are still where they were.
+const MOVED: Dictionary = {
+	# The top bar
+	"TopPanelContainer": "TopBar/TopPanelContainer",
+	"Title": "TopBar/Title",
+	"SearchButton": "TopBar/SearchButton",
+	"SyncButton": "TopBar/SyncButton",
+	"StatisticsButton": "TopBar/StatisticsButton",
+	"ShortcutsButton": "TopBar/ShortcutsButton",
+	"AboutButton": "TopBar/AboutButton",
+	"QRButton": "TopBar/QRButton",
+	# The popups of the main window, renamed from *Window to *Popup
+	"Search": "SearchPopup",
+	"SyncWindow": "SyncPopup",
+	"QRWindow": "QRPopup",
+	"ShortcutsWindow": "ShortcutsPopup",
+	"AboutWindow": "AboutPopup",
+	"Log": "LogPopup",
+	# The quiz and its parts
+	"Open": "Quiz/Open",
+	"FileDialog": "Quiz/FileDialog",
+	"DebugLabel": "Quiz/DebugLabel",
+	"MusicListPanel": "Quiz/MusicListPanel",
+	"Players": "Quiz/PlayersPanel",
+	"ScrollContainer": "Quiz/InspirationList",
+	"VBoxContainer": "Quiz/NowPlaying",
+	"MusicPlayer": "Quiz/MusicPlayer/PlayerBar",
+	"RepeatSongCheckButton": "Quiz/MusicPlayer/RepeatSongCheckButton",
+	"ResetPlaylistButton": "Quiz/QuizToolbar/ResetPlaylistButton",
+	"ResetPointsButton": "Quiz/QuizToolbar/ResetPointsButton",
+	"SettingsButton": "Quiz/QuizToolbar/SettingsButton",
+	"SoundTestButton": "Quiz/QuizToolbar/SoundTestButton",
+	"ShowAnswerButton": "Quiz/SongControls/ShowAnswerButton",
+	"NextButton": "Quiz/SongControls/NextButton",
+	"SettingsWindow": "Quiz/SettingsPopup",
+	"NewCharacterSelect": "Quiz/CharacterSelectPopup",
+	"WinnerWindow": "Quiz/WinnerPopup",
 }
 
-## Nodes that moved from the main window into the TopBar scene, by their old name.
-const TOP_BAR_NODES: Array[String] = [
-	"TopPanelContainer", "Title", "SearchButton", "SyncButton", "StatisticsButton",
-	"ShortcutsButton", "AboutButton", "QRButton",
-]
+## Scenes that were renamed, by their old and new root name. A row added to a list is
+## named after its scene's root when the name is still free, so these show up deeper in a
+## path.
+const RENAMED_SCENES: Dictionary = {
+	"SongListObject": "SongRow",
+	"Player": "PlayerRow",
+}
 
 ## How far a node may be from its old place, in pixels.
 const TOLERANCE: float = 0.5
@@ -71,14 +91,12 @@ func after() -> void:
 
 ## Where the node that used to be at [param old_path] in the main window is now.
 static func new_path(old_path: String) -> String:
-	var first: String = old_path.get_slice("/", 0)
-	if first in QUIZ_NODES:
-		return "Quiz/" + old_path
-	if first in RENAMED_QUIZ_NODES:
-		return "Quiz/" + RENAMED_QUIZ_NODES[first] + old_path.trim_prefix(first)
-	if first in TOP_BAR_NODES:
-		return "TopBar/" + old_path
-	return old_path
+	var parts: PackedStringArray = old_path.split("/")
+	for i: int in parts.size():
+		parts[i] = RENAMED_SCENES.get(parts[i], parts[i])
+	var first: String = parts[0]
+	parts[0] = MOVED.get(first, first)
+	return "/".join(parts)
 
 
 func _baseline() -> Dictionary: