Expressive mark improvements

• Hairpins in the style of Ferneyhough now support al niente circles.

  {
    \override Hairpin.circled-tip = ##t
    \override Hairpin.stencil = #flared-hairpin
    b1\< b\> b\> b2 b\< b2 b\!
  }
  

  

• Two new variant glyphs for breathing signs are available: ‘laltcomma’ and ‘raltcomma’. These glyphs represent the old shapes of ‘lcomma’ and ‘rcomma’, respectively, before changing them to more common shapes.

  {
    \override BreathingSign.text =
      \markup { \musicglyph "scripts.raltcomma" }
    f'2 \breathe f' |
  }