Issue 185: Remove Pitch_squash_engraver

Issue 185: Remove Pitch_squash_engraver

Actually, this issue is called "RhythmicStaff squishing chords should
produce single notes" and that's one thing that it does.  But in the
course of it, it completely replaces the Pitch_squash_engraver since
the Note_heads_engraver has to look at squashedPosition anyway in
order to decide how many note events to handle.

Articulations and fingerings on spurious noteheads get lost when
squashing.  It would be conceivable to transfer them to the remaining
note event, but it's not clear that this would not cause problems of
its own.

Contains convert-ly rules as well.


Additional commits:

Perfunctorily remove bad links to Pitch_squash_engraver in translations


A few documentation fixes after removing Pitch_squash_engraver


Run scripts/auxiliar/update-with-convert-ly.sh

[J. Rohrer, 2013-11-29 19:28:44]

To make sure I understand correctly (unfortunately I cannot test the patch right
now, I only looked over the diffs): After this change,

- you can still freely mix squashed and unsquashed voices in one staff,
- to squash notes in one voice, you just set Voice.squashedPosition to an
appropriate numeric value, and
- to stop squashing again, you set it to #f (anything non-numeric actually).

Correct?

If so, this is a nice simplification IMO.

[dak, 2013-11-29 23:31:56]

On 2013/11/29 19:28:44, J. Rohrer wrote:
> To make sure I understand correctly (unfortunately I cannot test the patch
right
> now, I only looked over the diffs): After this change,
> 
> - you can still freely mix squashed and unsquashed voices in one staff,

Yes.  The Pitch_squash_engraver actually does exactly that: if squashedPosition
is not set to a numeric value, it does nothing.

> - to squash notes in one voice, you just set Voice.squashedPosition to an
> appropriate numeric value, and
> - to stop squashing again, you set it to #f (anything non-numeric actually).
> 
> Correct?

Not "anything non-numeric": LilyPond will protest against most.  #f and #'() are
always permitted (#f switches off, and #'() defers judgment to the parent
context setting).

And it only affects Note_heads_engraver for now: Pitch_squash_engraver worked on
anything including custom engravers.  I did not see the point for
Drum_notes_engraver but may be convinced otherwise.

> If so, this is a nice simplification IMO.

The most logical simplification would have been
\override NoteHead.staff-position = #0
but that could not easily have been made to encompass the "leave only one
notehead" functionality.