Non-double glissando

[Helge Kruse]

The Lilypond snippet

http://lilypond.org/doc/v2.19/Documentation/snippets/expressive-marks#expressive-marks-double-glissando

shows how to get a double glissando. It add adds a second voice to draw
the glissando lines with hidden notes:

\relative c {
  \clef bass
  <<
    {
      % new voice ( = \voiceOne), hidden
      \hideNotes
      % attach glissando to note heads
      e2\glissando g
    }
    \\
    {
      % original voice with chords rearranged so that
      % glissando is attached to a & c
      <e a,>2\glissando <g c,>
    }
  >>
}

But the lower part designated with "original voice ..." is sufficient to
get the double glissando. I wanted just one glissando line connecting
the chords.

I have tested this with Lilypond 2.18.2 and 2.19.81. I wanted to check
this with older versions. But unfortunately the download site
(http://download.linuxaudio.org/lilypond/binaries) is down. Or the link
at http://lilypond.org/old-downloads.de.html is broken.

Best regards
Helge