Made it impossible to trigger a worldline shift during a worldline shift.

Edited the "blank" Nixie tube sprite to be one pixel higher, matching the others. Just in case.

The first digit now displays the same random animation as the other digits.
However, it will still be set to 0 or 1 at the end - this is purely a visual change.

The initial worldline is now picked at random.
Fixed the bug where the first worldline shift would sometimes show empty spaces for random digits.