PartCombine: Implement part-combine texts on the first real note (issue3285042)

[v . villenave]

Hi Reinhold,
it looks quite good; I only have minor comments so hopefully someone
more experienced than me will have more to say :)


http://codereview.appspot.com/3285042/diff/1/lily/part-combine-engraver.cc
File lily/part-combine-engraver.cc (right):

http://codereview.appspot.com/3285042/diff/1/lily/part-combine-engraver.cc#newcode49
lily/part-combine-engraver.cc:49: bool have_note;
Wouldn't "has_note" be more informative? Or perhaps I misunderstood the
logic here.

http://codereview.appspot.com/3285042/diff/1/lily/part-combine-engraver.cc#newcode102
lily/part-combine-engraver.cc:102: if (have_note || !to_boolean
(get_property ("partCombineTextsOnNote")))
Are you sure you want to use a plural in the property name? I'm not sure
that's what we do usually (other than "fretboards" etc.): see e.g.
tieWaitForNote, all singular.

http://codereview.appspot.com/3285042/