Fix #25958 - Crash when [Apply]ing and [OK]ing some prop changes

Additional fixes:

- Changes to staff own properties (small, invisible, user dist., colour) were not carried on.
- Changes to staff type when not visibly laid out into the score.
- Finally time sigs are re-laid out when staff type changes.
- If short and long names are empty strings, instrument relevant lists are no longer set to an empty string; rather the relevant list is left empty; this matches the situation when the dlg is open with either name not set and avoids unnecessary ChangePart undoes.
Merge pull request #960 from mgavioli/Fix_25958_EditStaff_crash_on_some_props_change

Fix #25958 - Crash when [Apply]ing and [OK]ing some prop changes