Make all the lily-library constants "safe"
To fix a score discovered at https://en.wikipedia.org/wiki/Prelude_and_Fugue_in_E_minor,_BWV_855 which used Staff.OttavaBracket.direction = #DOWN. I tested the fix locally.
To fix a score discovered at https://en.wikipedia.org/wiki/Prelude_and_Fugue_in_E_minor,_BWV_855 which used Staff.OttavaBracket.direction = #DOWN. I tested the fix locally.