mensural notation improvements (issue3797046)

[benko . pal]

Reviewers: ,

Message:
here is the patch set I hinted at several times:
http://lists.gnu.org/archive/html/lilypond-devel/2010-11/msg00212.html
http://lists.gnu.org/archive/html/lilypond-devel/2011-01/msg00097.html

some changes are just very slightly related:
mf/parmesan-custodes.mf just makes custodes longer (inspired by
Petrucci's Odhecaton, see
 http://imslp.org/wiki/Harmonice_Musices_Odhecaton_(Petrucci,_Ottaviano)

scm/parser-clef.scm adds Petrucci-like subbass clef

lily/ligature-bracket-engraver.cc is hair splitting over what to include
and what not.

the important ones:
mf/parmesan-noteheads.mf adds the noteheads

scm/output-lib.scm makes them usable as note head styles

the remaining ones add ligature support; to achieve it, I had to
reorganise the code, e.g. to create separate stencils for the two notes
of a flexa shape (oblique ligature); while at it, I did some todos as
well (removed join-right-amount) and added support for some
customization:
now the user can request flexa shapes even where they are not compulsory
by the ligature-flexa property and can control their size within a
ligature.  these properties must be set for the second note of the
flexa; I know it is ugly, but I don't have any better idea, since these
are properties of neither a single note, nor of the whole ligature.

test files: is it ok to modify existing regression tests?
I mean not only adding more, but changing in mensural-ligatures.ly the
Ockeghem examples to look more like the ones in codex Chigi, see scans
in attachment to
http://lists.gnu.org/archive/html/lilypond-devel/2010-12/msg00398.html

thanks,
p

Description:
mensural notation improvements

- support coloratio (even in ligatures)
- more flexible ligatura shapes

Please review this at http://codereview.appspot.com/3797046/

Affected files:
  M lily/include/mensural-ligature.hh
  M lily/ligature-bracket-engraver.cc
  M lily/mensural-ligature-engraver.cc
  M lily/mensural-ligature.cc
  M mf/parmesan-custodes.mf
  M mf/parmesan-noteheads.mf
  M scm/define-grob-properties.scm
  M scm/define-grobs.scm
  M scm/output-lib.scm
  M scm/parser-clef.scm