Doc: Appendix - Articulations and Ornamentation - part 1

Issue 1189

Create Texifo @multitable entries for the
List of Articulations appendix.

As there are a lot of separate scripts being
documented this Issue is going to be split
into multiple, smaller, parts to aid in the
review process.

This is part 1 and covers 'Articulation' and
'Ornament' scripts only.
Doc: Updated Roadmap file

Issue 3963

Added new Catalan translation

Updated existing descriptions for previous entries
including minor formatting changes.
Revert "Doc: Appendix - Articulations and Ornamentation - part 1"

This reverts commit 0cf0757b026ea6d7435a9cd837019291c6dee3d6.

Pushed by mistake. This checkin is still under review.

My apologies
doc: update make-simple-closure example in Extending (Issue 3993)

After improvements in Self_alignment_interface::aligned_on_parent
(in particular after fixing issue 3254) it was possible to simplify
default X-offset values for several grobs, so that they didn't have
to use make-simple-closure (see e.g. commit 1d765020f8679958). This
made an example in Extending 2.7 obsolete, so I'm replacing it with
one that still uses make-simple-closure.
Issue 2462: don't change ideal spacing when adding a rod

When objects like lyrics are added to the PaperColumns, LilyPond inserts
rods between these columns to ensure that the objects won't overlap.
However, the ideal distance should remain unchanged.  For example, in

\layout {
  ragged-right = ##f
}
\relative f' { \repeat unfold 8 a4 }
\addlyrics { \repeat unfold 4 la \repeat unfold 4 straight }

notes in 2nd measure have long lyrics attached to them - min_distance_
of the springs between these columns should be adjusted, but distance_
(the ideal distance) should not: it should be the same as for notes
with short lyrics.  When the line is stretched so much that the minimum
distances are not involved, the springs between notes in both measures
should behave (almost) identical.

Note that there are more such problems in the springs code, for example
in merge_springs.  The code should be rewritten, but that's not trivial.
Since this one-liner fixes some instances of the problem without any bad
side-effects, it makes sense to include it separately.
Issue 3958: Give examples of \applyContext usage.
Issue 3991: \magnifyMusic: surrender to issues 3987 and 3990.

Until issues 3987 and 3990 are fixed, automatic scaling
of horizontal spacing with \magnifyMusic is broken.  This
patch turns the feature off, and adds a note in the docs.
Issue 3997: \magnifyMusic: don't modify nested properties.

Also reformat Scheme code.
Issue 3996: Clarify 'thickness and 'line-thickness property docstrings.
Updates to GUB build instructions in CG
Release: bump VERSION_DEVEL.
PO: update template.
Release: update news.
Release: bump Welcome versions.
Merge remote branch 'origin/release/unstable' into HEAD
Release: bump VERSION.
Don't depend on features removed in Guile 2.1. (issue 3972)

* Replace scm_listify with scm_list_*. (It's been deprecated for a long time.)
* Use scm_protects only when available (Guile versions <2.1).