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.

log_popup.gd

@@ -0,0 +1,26 @@
+class_name LogPopup
+extends BasePopup
+
+@onready
+var log_panel: Panel = %LogPanel
+
+@onready
+var log_box: VBoxContainer = %LogVBoxContainer
+
+var log_rows: Array
+
+func add_log_row(text: String) -> void:
+	var log_row: String = get_time() + text
+	log_rows.append(log_row)
+	log_box.add_child(make_log_label(log_row))
+
+func make_log_label(row: String) -> Label:
+	var log_label: Label = Label.new()
+	log_label.add_theme_font_size_override("font_size", 20)
+	log_label.text = row
+	log_label.autowrap_mode = TextServer.AUTOWRAP_WORD
+	return log_label
+
+func get_time() -> String:
+	var time: Dictionary = Time.get_time_dict_from_system()
+	return "%02d:%02d:%02d " % [time.hour, time.minute, time.second]