Revised version of waveform renderer on Rietveld that uses glpk

[Mike Solomon]

http://codereview.appspot.com/1720046

Hey developers,
    Today I had time to finish version 2 of my waveform patch that uses glpk
to do smooth linear interpolation of waveforms.  As there is a dependency
freeze & glpk is ultimately too big & too everchanging to be part of
lilypond, this won't make it into 2.14, but I'd like to get it into a
development version ASAP.  I've already composed a piece w/ the old version
of the patch & the new version has rendered said piece even prettier.
    In making it, I've learned a great deal about linear and cone
programming and I think that there are many elements of lilypond, most
notably its traffic-coppery of intersections, that could be phrased in a
constrained semi-definite optimization program.  This may be a pet project
of mine later down the line, but for now, the current patch would benefit
greatly from your opinions and usage.
    The patch, which shows some (but not all) side-by-side diffs is up at:
http://codereview.appspot.com/1720046 .  Note that in it, I have a change to
include/lily-guile.hh that I needed to make for OS X to get the guile
ellipses to work (...) .  This can likely be removed w/o consequence,
although as I know next to nothing about guile, I have no clue what effect
this has - I just know that w/o it, lilypond didn't compile on my machine,
and I couldn't figure out a way to format the patch w/o picking this up.
    Anyway, please let me know what you think!!!  For ideas, check out
http://www.apollinemike.com/lilypond/waveform

~Mike