Web-es: typo.
Web-fr: typos in essay
Issue 3876: Fix shape of G clefs

This patch simplifies the code for the double G clefs; it also fixes the
incorrect test of the `double_shift' parameter that caused the non-double
G clefs being drawn twice.

Recent FontForge warnings like

  Internal Error (overlap) in clefs.G: Intersection failed!

or the ugly shape with a straight line instead of a curve in the left part
of the G clef are now gone: Drawing the shape twice triggered a bunch of
FontForge bugs.
Issue 3651: Simplify incipit.ly snippet

After issue 3187, considerably less trickery is needed for getting the
incipits to align with the main score.

(cherry picked from commit 14dbac1c794b04b8269229266f10c25438700349)
Issue 3648/2: Slight documentation amendment for RhythmicStaff in NR

(cherry picked from commit 2527d439536f4b4423dcb3324bb2bbbfa6c71662)
Issue 3655: Doc: Changes.tely 2.18 release

Mention new NullVoice feature including a simple example

(cherry picked from commit 0f7b01fc0bb37987e3405a7acbc14dc6aeb47d71)
Add Changes entry for -dstrokeadjust and "Usage" entry.

(cherry picked from commit 21142318024c3abac5a13adaf32233cc741683cb)
CG: remove information about frogs and frog meister

frogs list is dead, and the frog meister was a good idea
but it gets out of touch from reality (since a few months
previous Frog Meister didn't actually participate in development).

(cherry picked from commit fcad9f183bb05f7206427bf5fc1b95fd8209d26e)
documentation: staff-spacing, resolve collisions

(cherry picked from commit 03c026361826478e7e19130f7ed732a243f38a63)
Doc: Add links to LP user blog for Video Tutorials

Issue 3540

Added referfences and links to Video Tutorials
for beginners via LilyPond user Ben Lemon's blog

(cherry picked from commit ec87e9088a9ae23dad5e9b84a9078a10e81c1e8f)
Doc: Add mention of LibreOffice

Issue 3686

OooLilyPond works for LibreOffice as well as OpenOffice.

(cherry picked from commit 4d7364b28f3059a2caa9f31fb491d8556d9d2d33)
Web: Add 3 published productions by Joe Smeets

Issue 3657

Introduction.itexi

(cherry picked from commit cf106d041fe91a674a850b720453475696384dee)
Web: Iintroduction.itexi - Minor typos

LilyPond not lilypond

(cherry picked from commit 787aac98e6e981983ae8a9b392e2656209ac38a0)
Web: Reword contactUsAbout macro

Providing information on new reviews/productions etc.
should be possible by simply writing an email to bug-lilypond.
Redirecting to the Bug Report guide is off-putting.

(cherry picked from commit b5f1e7677d0bd21b548d1b59284759b6e520ff69)
Typo fix in NR

(cherry picked from commit b2e692060d97b87f58c6f3fe6938688725d590fa)
Issue 3719: CG: Add comment about git-cl editor

git-cl fires either the editor specified by the
EDITOR environment variable or vi if EDITOR isn't defined.
Commit mentions this in the CG

Signed-off-by: David Kastrup <dak@gnu.org>
(cherry picked from commit 5155adb1fe43e2b166c3101ad48f05d502eef31a)
Web: What we wrote... Book about LP in Turkish

Came from message

URL: http://lists.gnu.org/archive/html/bug-lilypond/2013-12/masg00051.html

Professor Server Acim's book in Turkish about LilyPond

(cherry picked from commit 90dd3d2819f150449a6e39665c654755bc70653a)
Web: Improve notes about Linux Dist LP Packages

Issue 3735

Explain that LP in most Linux Repositories is going to be
older than the current available code on the LP website

(cherry picked from commit 681b14e151ada14fa98d5aed413aae4e5e4b9848)
Doc: Usage add .vimrc syntax highlighting

Issue 3492

(cherry picked from commit 751b3bce9e954e926365842098c5c170b14317c9)
Doc: Add @knownissue for AddLyrics with Nullvoice

Issue 3654

(cherry picked from commit 196a1ace684e52c3f6bab452780f90ff405b5564)