issue 3692: Fingering collision with accidentals (issue 341470043 by address@hidden)

[torsten . haemmerle]

Reviewers: ,

Message:
Please review.

Thanks,
Torsten

Description:
issue 3692: Fingering collision with accidentals

Changes to be committed:

modified:   ../Documentation/changes.tely
  - Announcing the new X-align-on-main-noteheads feature
    for the New_fingering_engraver

new file:   ../input/regression/fingering-adjacent-note-chord-new.ly
new file:   ../input/regression/fingering-adjacent-note-chord.ly
  - Adjacent-note chord regression tests for New_fingering_engraver
    and Fingering_engraver.

modified:   ../lily/fingering-engraver.cc
  - Instead of aligning the fingering on the first-to-come notehead of
the
    chord, now use note-column as parent and take advantage of the
    side-position-interface's X-align-on-main-noteheads functionality.
  - The (sometimes) incorrect alignment caused by simply using the the
    first chord note entered as parent was, after all, the actual reason
    for the accidental collision that never had happened with a proper
    fingering alignment.

modified:   ../lily/new-fingering-engraver.cc
  - Making New_fingering_engraver consider the X-align-on-main-noteheads
    property and use note-column as parent for up/down orientations.
That
    way, up/down fingerings will be aligned in a straight column,
properly
    centered over the main noteheads.
  - With "classic" per-note alignment, use  notehead as parent (as it
had
    been always done), but now avoid all accidentals in the chord for
    up/down placement.
  - If there's only one note, no special alignment/accidental treatment
    needed.
  - accidentals_.clear () had been missing after position_all (), so
that
    more and more accidentals gathered up from chord to chord.
  - By default, X-align-on-main-noteheads is *not* set to keep
everything
    compatible to the previous practice.
  - When setting X-align-on-main-noteheads and using just up/down
orientation,
    New_fingering_engraver behaves like Fingering_engraver.

Please review this at https://codereview.appspot.com/341470043/

Affected files (+116, -6 lines):
  M Documentation/changes.tely
  A input/regression/fingering-adjacent-note-chord.ly
  A input/regression/fingering-adjacent-note-chord-new.ly
  M lily/fingering-engraver.cc
  M lily/new-fingering-engraver.cc