C64, C128, Plus/4 versions updated

Commodore 64, Commodore 128 and Commodore Plus/4 versions have been updated. There are no changes to the game, but the package now includes a .d81 file with the same contents as the .d64 file.

The difference lies in save file storage. If you're using the .d81 file, it is safe to save on the same disk; with the .d64, please use a blank disk to store saves. (This should fix a problem some of you might have been having with SAVE/RESTORE; apologies for not making it clearer sooner.)