NR 2.4.1, Default tablatures: harmonics notes in Staff are one octave lower

[Federico Bruni]

Hi

in the three harmonics snippets below, the pitches in Staff are not 
correct, at least for a guitar:

http://lilypond.org/doc/v2.15/Documentation/notation/common-notation-for-fretted-strings#index-_005charmonic-2

We should add \clef "G_8", like in this example:

\layout { \override Voice.StringNumber #'stencil = ##f }
firstHarmonic = {
  d'4\4\harmonic
  g'4\3\harmonic
  b'2\2\harmonic
  a,
  \harmonicByFret #7 a,2\5
}
\score {
  <<
    \new Staff { \clef "G_8" \firstHarmonic }
    \new TabStaff { \firstHarmonic }
  >>
}