* scripts/lilypond-book.py (Lilypond_file_snippet.ly): don't copy

* scripts/lilypond-book.py (Lilypond_file_snippet.ly): don't copy
file contents, rather \include them, so default linewidth is set.
(ly_options): make BOOKPAPER set of options. Move linewidth
settings there.

* Documentation/user/examples.itely: new file. Templates are to be
moved here.

* Documentation/user/programming-interface.itely: move chapter.

* scm/document-markup.scm (doc-markup-function): add @code

* stepmake/stepmake/texinfo-rules.make: remove chmod.