\stemUp with mensural longa

[JMarc]

Hi !

The lily french list has tested and approved a piece of code allowing to have a
stemUp with mensural longa. Would it be possible to include it in Lilypond so it
may be possible to just code : \stemUp a\longa ?

Here's the code : 

\version "2.11"
longaNote = #(define-music-function (parser location note)
                                          (ly:music?)
       #{
         \once \override Voice.NoteHead #'stencil =
           #ly:text-interface::print
         \once \override Voice.NoteHead #'text =
           \markup \musicglyph #"noteheads.slmensural"
         \once \override Voice.Stem #'stencil = ##f
         $note
       #})
\header {
  title = "Longa avec hampe vers le haut"
  tagline = \markup{ \italic {\teeny {gravure JML - 12/08 - Lilypond 2.11}}}
} 

#(set-global-staff-size 22)
       
global = {
\once \override Staff.TimeSignature #'style = #'neomensural
\override Voice.NoteHead #'style = #'neomensural
\override Staff.Accidental #'style = #'neomensural
\cadenzaOn
\time 2/2
}

notes = \relative c'' {

\clef "petrucci-c1"

g4 g d' d e e d2 c4 c b b a a \override NoteHead #'rotation = #'(180 0 0)
\longaNote a
}

\score {
\new Staff <<
\override Staff.VerticalAxisGroup #'minimum-Y-extent = #'(-5 . 20)
\set Staff.instrumentName = \markup {\tiny \italic "Dessus de viole"}
{\global \notes} >>

}


Merry Christmas !

JMarc