[PATCH] Implement MusicXML files in lilypond-book

[Reinhold Kainhofer]

Please review:
http://codereview.appspot.com/1659041/


This patch adds support for including MusicXML files into 
documents processed by lilypond-book. In particular:
-) HTML: <musicxmlfile options>filename.xml</musicxmlfile>
-) TeX: \musicxmlfile[options]{filename.xml}
-) Texinfo: @musicxmlfile[options]{filename.xml}

Since MusicXML is so verbose, it doesn't make much sense to 
support inline MusicXML.

The snippets are first processed by musicxml2ly and then 
treated like a normal lilypond snippet in lilypond-book.
The only difference is that the original .xml file is linked
in the output rather than the intermediary .ly file.

I have mainly implemented this so that the MusicXML test 
suite can directly link to the .xml file files rather than the 
lilypond files, which are not relevant for xml anyway.

I have also extended lilypond-book to allow additional 
formatters, so the MusicXML test suite can override the 
formatting of the MusicXML snippets in the output (e.g. 
because I want to add some to other renderings in the future, 
too).

Cheers,
Reinhold
-- 
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Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org