Re: Adds redirect-lilypond-output option to lilypond-book (issue4664060)

[percival . music . ca]

in light of the growing consensus for "combined" logfiles for the build
system -- and given that lilypond only produces stuff on stderr and
apparently this isn't going to change -- I wonder if it might be better
to redirect both stdout and sterr to a single .log file.

I'm happy with pushing this patch as-is and changing this later, though.

http://codereview.appspot.com/4664060/