Editorial annotation improvements

• Incipits may be printed with various context types.

  \score {
    <<
      \new Staff \with { instrumentName = "MensuralStaff" }
        {
          \incipit { c'4 d' }
          c'4 d' e' f' g'1
        }
  
      \new Staff \with { instrumentName = "KievanStaff" }
        {
          \incipit \new KievanStaff { c'4 d' }
          c'4 d' e' f' g'1
        }
      \new Staff
        \with { instrumentName = "TabStaff" }
        {
          \incipit
            \new TabStaff
              \with { \magnifyStaff 0.5 \override InstrumentName.font-size = 6 }
              { c'4 d' }
          c'4 d' e' f' g'1
        }
    >>
    \layout {
      indent = 5\cm
      incipit-width = 2\cm
    }
  }
  

  

• Optional additional material can be enclosed in brackets that pass through the staff with \startOptionalMaterial and \stopOptionalMaterial.

  

• The FingerGlideSpanner may now connect StringNumber and StrokeFinger grobs.

  {
    \set strokeFingerOrientations = #'(down)
    b2 \glide -\rightHandFinger #1 \glide -2 \glide \5
    e'-\rightHandFinger #1 -2 \5
  }
  

  

• NoteName grobs are now horizontally centered by default.