Issue 3584: Let convert-ly -d reflect last effective rather than last applied rule
LSR reimport because of issue 3584 changing version numbers
Issue 3566: Grace notes should be autobeamed

This works by adding a Grace_auto_beam_engraver that considers an
entire grace phrase as one autobeam group.
Add Grace_auto_beam_engraver to default engravers for Voice
Add one-time convert-ly rule for grace beaming
Run scripts/auxiliar/update-with-convert-ly.sh
Revert "Add one-time convert-ly rule for grace beaming"

This reverts commit bbdf994d643ea96c3cabfb40fbe2f4d22af93233.

The convert-ly rule was only intended for making our documentation
somewhat snappier.  Since it is only intended to remove manual
beamings that have now become redundant, it's mainly interesting for
documentation rather than user-level documents.
Manually revert bad convert-ly change for input/regression/lyric-combine.ly
Add reference to Grace_auto_beam_engraver to Notation/Rhythms
Add regtest for Grace_auto_beam_engraver
Issue 2931: Allow non-LilyPond identifiers like "violin1" to be called as \"violin1"

A frequent complaint is the absence of identifiers with numbers in
them, like violin1.

Defining such identifiers has always been possible with

    "violin1" = { c''4 c c c }

This patch lets one actually use them by calling them as

    \"violin1"
Add regtest for quoted identifiers
Change option description -x,--long-option to -x, --long-option consistently
Release: bump VERSION_DEVEL.
PO: update template.
Release: update news.
Release: bump VERSION.
Remove unused data from Completion_heads_engraver and Completion_rest_engraver
Issue 3593: Announce ends of ties in Completion_heads_engraver
Issue 3115: Revert "Uses a heuristic to determine if chord tremolos collide with accidentals."

This reverts commit d8dfa746ead381a80901106b9c9b079dc9b5d004.

Conflicts:
	scm/define-grobs.scm

But reconstitute input/regression/chord-tremolo-accidental.ly.  Not
done in a separate commit in order to preserve blame.