indent in lilypond-book

[Graham Percival]

Between 2.3.18 or so (maybe as late as .20 or .22) and .25, 
lilypond-book no longer indents the first line in long (two-page) 
scores in latex documents.

If that's a design decision, groovy; I'll change section 9.5 
accordingly.  If it's a bug (and marked "wontfixyet"), then I should 
add a BUGS section to 9.5.

Cheers,
- Graham