[Muine] part support [patch]

[Jeff Garrett <jgarrett math uchicago edu>]

First, I should say I like muine a lot.  Thanks for all the work.  I
thought the patch [4] might be interesting to others.  Below is the
justification & details.

Thanks again,
Jeff

A large part of my music collection is classical music, with the various
parts/movements split up into different tracks.  This gets ugly (and
overwhelming) in the Muine playlist, each title being so long.  [Imagine
trying to find the start of Beethoven's Symphony No. 5, given that
you've got all of Symphonies 1 - 9 in the playlist, 3 or 4 movements a
piece, and almost all of the information is exactly the same except for
one measly number.  Obviously that is extreme, but I still find it hard
to find the "starts" of things when I load many songs into the playlist
and each have a few parts.]

So I made a quick hack to support the PART tag (see [1]).  It now looks
more sane (screen shot [2]).  If the song has no PART tag, it displays
as before
"<b>$title</b>\n$artists"
in the playlist window.  If it has a PART tag and is the first song, or
is not a part of the song that comes before it, it will display
"<b>$title</b>\n$artists\n    $part"
If it is a part of the song before it, it just displays
"    $part"
(It seems better to use \t than some amount of spaces, but for some
reason this didn't indent uniformly...  see [3].  Why?)

In the Add Song window, if a song has a part, it gets displayed as
"<b>$title $part</b>\n$artists"
(which is as much as was there before)

Also, I find it easier to find things sorted by artist, then discname in
the Add Album window.  [I'm more likely to know my CDs of Liszt's
transcriptions of Beethoven's Symphonies are titled that, than that it
is performed by Konstantin Scherbakov.]  This doesn't affect very much
(one can always search), but the sort used to seem more random and now I
can find more easily what I look for.   Anyways, the patch below also
contains this 1-line "fix".

Bugs/limitations:
I only implemented reading the PART tags for the ogg vorbis files.
It only compares Title and /first/ Artist to determine if it's the same
song.  It really should compare all artists.
Some funny business seems to happen when songs are removed.
My code is ugly/hacky.
Since some songs now get more screen space, there might be some
usability issues (different sized targets).  I do think there is a
positive tradeoff here, as previously there was too much information
(Symphony this or that) drowning out the specifics.

[1] http://www.gophernet.org/articles/vorbiscomment.html
[2] http://www.math.uchicago.edu/~jgarrett/code/shot-part.png
[3] http://www.math.uchicago.edu/~jgarrett/code/shot-indent.png
[4] http://www.math.uchicago.edu/~jgarrett/code/muine.diff