Resetting @exampleindent to `5' gives ugly results with texinfo's

Resetting @exampleindent to `5' gives ugly results with texinfo's
DVI output.  Use `@format @exampleindent 0 ... @end format' instead
(if not quoting) to change @exampleindent only locally.

* scripts/lilypond-book.py (NOQUOTE): New variable.
(output) [LATEX]: Remove AFTER and BEFORE.
[TEXINFO]: Remove AFTER and BEFORE.
Fix QUOTE and VERBATIM pattern.
Add NOQUOTE pattern.
(Lilypond_snippet) [output_info, output_latex]: Don't handle AFTER
and BEFORE.
[output_texinfo]: Use NOQUOTE.