Fix missing initial in staff names

[tobylane]

Fixes #2554

Describe what the proposed change does

• When the number used to pick a staff initial is 0, make it 1. Apply this to existing staff.

[TheCycoONE]

I think the proper fix here is + 1, otherwise no one gets the last entry and the first is twice as often. To preserve existing names the table can be shifted.

[tobylane]

The last entry, which is never used, is copied to the 0th position. This keeps the order and fills the initials table the way it's needed, from 0.

[TheCycoONE]

Yeah that works.