Pitches improvements (LilyPond Changes)

### Pitches improvements

- The new `\approximatePitch` command creates notes of approximate pitch.

  >     \relative c'' {
  >       e4 f g \approximatePitch c
  >     }

- Certain spurious change clefs have been fixed.

  >     {
  >       R1
  >       \clef treble
  >       R1
  >     }

#### LilyPond Changes v2.26.0 (stable-branch).

- Major changes in LilyPond
  - Notes for source compilation and packagers
- New for musical notation
  - Pitches improvements
  - Rhythm improvements
  - Expressive mark improvements
  - Repeat improvements
  - Editorial annotation improvements
  - Text and font improvements
- New for specialist notation
- Miscellaneous improvements