Bugfix release - Loading +3Dos Floppy disk

Fixed Loading of blank +3DOS/CPM Floppy disks. Basically it was checking for valid directory entries, which of course there aren't on a blank disk. Changed so its checking the actual DIRENTS for valid UserID values instead.

Normally, there wouldn't be a new release for a minor bug like this, but its part of the workflow for another project of mine, so meh...