Fixed <flash> command.

When flashing an already visible asset, the asset
would disappear after the flash.
Insert stage before restoring save states.

It makes more sense this way because assets can
re-configure themselves directly when their
restore() method is invoked.
Fixed: audio stopped playing after save state restore.

When a save game state was restored in which audio
was playing, the audio would not start again after
loading the save game.
Fixed DOM error when restoring texboxes from save state.

When loading a savegame, the restore() method of
textbox assets would through a DOM error because
the cssid property of the textbox asset still used
the object's ID rather than the asset's name.