Corrects puzzle filename in levels/default.xml
In order to show puzzle 'Pirate ship' when loading a game, filename 'old_ship.xpm' was replaced with 'pirate_ship.xpm' in levels/default.xml.
In order to show puzzle 'Pirate ship' when loading a game, filename 'old_ship.xpm' was replaced with 'pirate_ship.xpm' in levels/default.xml.