Release: bump VERSION_DEVEL.
Release: bump Welcome versions.
PO: update template.
Release: update news.
Minor update to Gregorian section of NR
Rename argument to avoid preprocessor problems

Before this change, we were getting the following error with GUB:

/home/gub/gub/target/mingw/src/
lilypond-git.sv.gnu.org--lilypond.git-release-unstable/
lily/include/paper-column.hh:62:
error: expected identifier before ',' token
/home/gub/gub/target/mingw/src/
lilypond-git.sv.gnu.org--lilypond.git-release-unstable/
lily/include/paper-column.hh:62:
error: two or more data types in declaration of 'parameter'

David Kastrup suspects that the library/compiler used for bootstrapping
has a macro or reserved word defined for "interface" - changing the name
makes the problem go away.
Issue 3968: Improve output of scheme-engraver.ly regtest.
Extending: 2.3.2 - Music Function usage

Issue 3955

Added words to sentences for clarity. (Hopefully) Improved sentence
syntax and some minor grammer nits.
Snippet: Update 'Create Delayed Turn' snippet from old syntax

Issue 3970

Updated all the ovverride AccidentalSuggestion settings so that they
now use the later accepted syntax supported by the parser.

font.size and script.size overrides will work with or without the '#'
symbol, so I have removed it in this example just to illustrate this.
Makelsr.py run

For previous commit 7e23569bfbb6502bb2e3d6f09f089fdb968b6d55
Merge remote branch 'origin/master' into release/unstable
Release: bump VERSION.
Reg Tests: XML 01b has an incorrect number of measures

Issue 3973

01b-Pitches-Intervals.xml from the Unofficial MusicXML
test suite contains only a single measure in MusicXML,
but there should be 41.

musicxml2ly is very tolerant here so the error doesn’t
show in the pdf.

Added missing <measure> elements
Fixed a typo in the title
Added missing <accidental> elements (They represent
the actual notated accidentals.  Without these elements
there shouldn’t be any visible accidentals. So this is
actually a bug in musicxml2ly. The bug doesn’t show here
because musicxml2ly interprets the <alter> element which
represents the sounding pitch of a note.)

Fixes provided by Patrick Schmidt
Reg Tests: XML 02a fix incorrect last note duration

Issue 3974

Unofficial MusicXML test suite shows incorrect last not duration
the last note was duration 2 (undotted 64th) but shows dotted 128th

Added some missing <type> elements
Corrected the durations of the last measure

Fixes provided by Patrick Schmidt
Clean up DynamicText horizontal alignment.

Until now, DynamicText alignment was messy, as there were 3 different
callbacks involved - some of them interacting in a confusing way:
 - in define-grobs.scm, X-offset property was initialized to
   ly:self-alignment-interface::x-aligned-on-self,
 - Dynamic_engraver called set_center_parent on every DynamicText
   attached to a note, so that half a NoteHead width was always added
   to its X-offset (producing confusing results for example when
   user requested dynamics to be left-aligned),
 - DynamicTexts living in a Dynamics context used a completely
   different offset callback, which aligned them on NoteColumns.

Since aligned_on_parent is now able to correctly align grobs
with PaperColumn parents (issue 3254), we can use it for all
DynamicTexts and have a single interface for the job.

Expected changes in output: DynamicTexts in Dynamics context
aligned to suspended noteheads may be placed up to 1/4 NoteHead
width further to the right.  This shouldn't be a problem.
Replace XY-offset closures with aligned_on_parent where possible

It doesn't make sense to specify placement using multiple added
callbacks or closures when we can use aligned_on_parent. What's
more, aligned_on_parent should expose more consistent interface
for the users - affected grobs should now behave similarly to
LyricTexts and DynamicTexts. For example, this

\relative c'' \context Voice {
  \compressFullBarRests
  \override MultiMeasureRestNumber.self-alignment-X = #RIGHT
  R1*100
}

will result in right edge of the MultiMeasureRestNumber being
aligned on the right edge of the MultiMeasureRest.

Affected grobs:
- AccidentalSuggestion
- ClefModifier
- DoublePercentRepeatCounter
- Fingering
- GridLine
- MultiMeasureRestNumber
- MultiMeasureRestText
- PercentRepeatCounter
- StemTremolo

Expected changes in output: none.
TextScript, CombineTextScript: use aligned_on_parent

I think this makes more sense than just using "self-alignment".
It makes these grobs consistent with Lyrics and Dynamics, and
allows users to override their alignment more predictably.

Expected changes in output: TextScripts and CombineTextScripts
will be aligned slightly different when the user sets self-alignment-X
explicitly (parent notehead will be included in alignment, as in Lyrics).
Default placement should remain the same.

I'm also changing one regtest, just to make sure that despite slightly
changed alignment the markups will stick out far enough to the left.
define-grobs.scm: reorder properties alphabetically
Issue 3978: Merge alignment cleanup

Make DynamicTexts, TextScripts and many other grobs use aligned_on_parent,
which makes their behaviour consitent, predictable and thus more user-friendly.
Issue 3942: Scale slurs and ties when using \magnifyMusic.