ly.pkginfo.name still in use

[Federico Bruni]

@jeanas In #155 you removed ly.pkginfo.name, but this is still used here:

$ git grep -n 'ly.pkginfo.name'
ly/musicxml/create_musicxml.py:58:        software.text = ly.pkginfo.name + " " + ly.pkginfo.version

This is causing troubles to a user trying to export a lilypond file to XML.

[Jean Abou Samra]

Sorry about this. I've pushed the (trivial) fix as 233de7e.