convert to Lua; this one creates several actors cleanly, and uses upvalues

stepmania/Themes/default/Graphics/ScreenWithMenuElements stage/default.lua

@@ -0,0 +1,16 @@
+local stages = { }
+for _, s in ipairs(Stage) do
+	if GAMESTATE:IsStagePossible(s) then
+		local t = LoadActor("_stage " .. s)() .. {
+			InitCommand = cmd(playcommand,"Update"),
+			CurrentSongChangedMessageCommand=cmd(playcommand,"Update"),
+
+			UpdateCommand=cmd(hidden,GAMESTATE:GetCurrentStage() == s and 0 or 1)
+		}
+		table.insert( stages, t )
+	end
+end
+
+return Def.ActorFrame {
+	children = stages
+}