Scheme chapter: material for deletion

[Graham Percival]

I believe that the material in section 11.6
http://lilypond.org/doc/v2.9/Documentation/user/lilypond/OLD- 
STUFF.html#OLD-STUFF

is either hopelessly out of date or irrelevant (due to  
#(define-music-function)).  If nobody speaks up support of this  
material, I will delete it in a week or so.

Cheers,
- Graham