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.

song_row.gd

@@ -0,0 +1,50 @@
+class_name SongRow
+extends PanelContainer
+
+@onready
+var song_list_label: Label = $HBoxContainer/SongListLabel
+
+@onready
+var song_list_players: HBoxContainer = $HBoxContainer/SongListPlayers
+
+var song_object: SongObject
+
+#Color(0.18, 0.18, 0.18)
+#Color(0.302, 0.302, 0.302)
+#Color(0.259, 0.259, 0.259)
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	#if song_object != null && song_object.song_number % 2 == 0:
+	#	var new_stylebox_normal = self.get_theme_stylebox("panel").duplicate()
+	#	new_stylebox_normal.bg_color = Color(0.18, 0.18, 0.18)
+	#	self.add_theme_stylebox_override("panel", new_stylebox_normal)
+	#	song_list_label.add_theme_stylebox_override("normal", new_stylebox_normal)
+	#else:
+	#	var new_stylebox_normal = self.get_theme_stylebox("panel").duplicate()
+	#	new_stylebox_normal.bg_color = Color(0.18, 0.18, 0.18)
+	#	self.add_theme_stylebox_override("panel", new_stylebox_normal)
+	#	song_list_label.add_theme_stylebox_override("normal", new_stylebox_normal)
+	set_label()
+	update_players()
+
+func set_label() -> void:
+	if song_object != null:
+		var size_to_change: int = song_object.players_given_point.size() * 50
+		song_list_label.custom_minimum_size = Vector2(1000 - size_to_change, 28)
+		if song_object.is_playing:
+			song_list_label.add_theme_color_override("font_color", Color(1, 0.5, 0))
+		song_list_label.text = song_object.get_song_info()
+
+func update_players() -> void:
+	Settings.delete_children(song_list_players)
+	if song_object != null:
+		# Show players in the same order as the player list
+		for player: PlayerObject in Settings.player_array:
+			if song_object.players_given_point.has(player.id):
+				var texture: TextureRect = TextureRect.new()
+				texture.texture = player.character
+				texture.expand_mode = TextureRect.EXPAND_FIT_WIDTH_PROPORTIONAL
+				texture.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_CENTERED
+				texture.custom_minimum_size = Vector2(50, 25)
+				song_list_players.add_child(texture)