Merge pull request #14 from PeterBjuhr/master

using \note instead of \note-by-number
hairpin: add snippet from LSR
hairpin: convert-ly to 2.17.29
hairpin: support custom alignments
hairpin: format with Frescobaldi
hairpin: small changes and rewrite the example
hairpin: add a disrecommendation from Gould
late evaluation: use macro

(quoted from David's email):
I don't consider most uses of eval a good idea anyway, but
making bad ideas work as expected is still an impressive feat.

Actually, since there is Scheme syntax creeping in anyway, it might make
more sense to use Scheme macros here and have less quoting blurb, and in
particular not the ugly eval.