Issue 3645: Allow \partial to occur in mid-piece

This is done by moving measurePosition to negative values when at the
beginning of a measure, and to a respective distance before the end of
the measure in case the measure has already been started.
Document in-piece use of \partial
Doc-it:  update
Issue 355: \repeat bar lines get messed up

% the second repeat should start at the beginning of a bar, not
% continue from the incomplete bar in the first ending.

\version "2.17.30"
\new Staff \relative {
  \partial 4
  \repeat volta 4 { e' | c2 d2 | e2 f2 | }
  \alternative { { g4 g g } { a a a a } }
  a b2.
}
Doc: External.itely - add missing comma

Typo

No tracker issue
PO: update from FTP
 Esperanto, Spanish, French and Italian
Doc: External.itely - add missing comma

Typo

No tracker issue
Merge remote-tracking branch 'origin/translation' into master
Issue 3649: Fill in section "\set vs \override"
Issue 3649: Fill in section "\set vs \override"
Issue 3644: A \score-lines markup list command for multi-lines embedded scores

Originally requested as issue 1334.

Like the \score markup, \score-lines is not called through the normal
markup list command mechanisms as it would require something awkward
along the lines of

\score-lines ##{ \score { ... } #}

to get this through.  Instead, a reserved word \score-lines in the
parser will manually call the command with an embedded score, leading
to just

\score-lines { ... }

This is somewhat clumsy in several ways: it requires an additional
reserved identifier (no other reserved identifier contains a dash),
and it means that a score may occur in a file without an explicit
enclosing \score command.

Nevertheless, the previous semantics implemented as issue 1334 were
not tenable: particularly after issue 3270 had been passed, it was
close to impossible for the average user to come up with a way of
getting an actual markup list from a score.

Note that there are as of yet no user-level commands spacing a markup
list in a way similar to the spacing inside of a \score markup.
Issue 3651: Simplify incipit.ly snippet

After issue 3187, considerably less trickery is needed for getting the
incipits to align with the main score.
Run scripts/auxiliar/makelsr.py
web: hotfix broken links in 2.17.95 announcement
Doc-fr: Issue 3649: Fill in section "\set vs \override"
Let #{ 4 #} be a duration while #{ 4 \cm #} stays a length

An UNSIGNED not followed by a NUMERIC_IDENTIFIER inside of #{ ... #}
is interpreted as a duration rather than a number.  Also, inside
of #{ ... #} no "numeric expressions" using binary operators +-*/ are
interpreted.

The behavior of (signed and unsigned) integers and numeric expressions
in assignments and as function arguments rather than inside
of #{ ... #} is not affected.
Use #{ 4 #} and #{ c #} for duration/pitch in optional-args regtest
Interpret #{ -3 #} as postevent rather than negative number

Since #{ 4 #} is interpreted as duration rather than number, interpreting
negative integers as numbers rather than fingering is not really helpful.
Issue 3648/1: Isolated durations in music sequences now stand for unpitched notes

This allows for things like

\new RhythmicStaff { 4 4. 8 4 | 4 \tuplet 3/2 { 2 4 } 4 }

"unpitched" simply means that this is rendered as a normal NoteEvent,
but the pitch information is missing and has to be filled in by some
other means.  The example using RhythmicStaff is not actually
commendable as the MIDI rendition still requires a pitch or drum
type.  It's just that as of this patch, there are no immediately
useful applications.  The rhythmic shorthand { c4 4. 8 4 } is
introduced by a later patch.
Issue 3648/2: Slight documentation amendment for RhythmicStaff in NR