[PATCH] Mensural Flags

[Juergen Reuter]

Hi!

Below is a patch for 1.5.7 that introduces mensural flags.  However,
there are some open issues:

* There is no mensural 32nd or 64th note, but only fusa (8th) and
  semifusa (16th).  For completeness, I have nevertheless tried to
  design flags for 32nd and 64th, although they are my pure invention
  and unfortunately look a bit ugly.  Maybe you prefer to exclude
  them.

* I could not find any Petrucci semifusa, but only a semifusa of a
  not-so-nice print and in bad resolution.  Hence, my semifusa flag is
  a kind of interpolation between Petrucci's fusa flag (taken from
  Gombert, Missa De Media Vita, 1542), and some not-so-fine semifusa
  flag.  If somebody has a high-resolution facsimile of a Petrucci-like
  semifusa, please let me know.  I might then also enhance the 32nd
  and 64th flags.

* Petrucci (and other printers) used flags that are different for
  notes on staff lines and for notes between staff lines.  Obviously,
  the idea is to have each flag nicely aligned vertically with the
  staff lines, regardless of the y position and length of the stem.
  Consequently, there are four flags for each note (two up, two down).
  An additional "0" or "1" character in the font symbol name is used
  to differentiate between them.

* This requires special treatment for mensural flags, currently
  reflected by an if-statement with a hard-coded "mensural" string in
  stem.cc.  This is ugly, but I do not see any clean solution other
  than introducing yet another scheme function.

* ancient-font.ly now produces many "programming error: No spring
  between column XYZ and next one (Continuing; cross thumbs)", but the
  result looks ok.  This did not happen in 1.5.6 (under which I
  developed this patch).  Is this a bug in the simple spacing
  algorithm?

Greetings,
            Juergen

patch.txt
Description: Patch