Ancient bar lines

[Dan Eble]

Jürgen and all,

I've attached two images of the first system produced for regression test 
input/breathing-sign-ancient.ly and included the relevant portion of the input 
below.

The current version of master adds some horizontal space after every fourth 
note.  It happens because there are transparent "|" bar lines there.


It is easy to eliminate those spaces by changing the default bar line to "" in 
gregorian.ly, and the other attached image shows the result.  I am willing to 
create a ticket and submit the change for review, but I don't have the 
background to judge whether a change is desirable.


Regards,
Dan

\version "2.19.21"

\header{
  texidoc="
Gregorian chant notation sometimes also uses commas and ticks, but in
smaller font size (we call it `virgula' and `caesura').  However, the
most common breathing signs are divisio minima/@/maior/@/maxima and
finalis, the latter three looking similar to bar glyphs.
" }

\include "gregorian.ly"

\context VaticanaStaff {
  \relative {
    % here is no \breathe
    c' g c

    % \virgula applies rcomma, but in a smaller font
    c \virgula g c

    % \caesura applies rvarcomma, but in a smaller font
    c \caesura g c

    % \divisioMinima is a simple vertical stroke through the
    % uppermost staffline, just like the original implementation
    % of breathing signs.
    c \divisioMinima g c

    % \divisioMaior, \divisioMaxima and \finalis look like bars and
    % are vertically centered on the staff; the direction property
    % has no effect
    c \divisioMaior g c
    c \divisioMaxima g c

    % this one looks almost like a "||" type bar
    \finalis
  }
}