* python/lilylib.py (make_ps_images): only compute bbox when needed.

* python/lilylib.py (make_ps_images): only compute bbox when needed.

* scripts/lilypond-book.py (process_snippets): use lily -f ps
files for generating pngs.

* scm/framework-ps.scm (output-classic-framework-ps): dump EPS
file with PFA fonts included.

* lily/score.cc (default_rendering): put header in too.

* lily/paper-line.cc (LY_DEFINE): change function to
ly:paper-line-extent

* scm/page-layout.scm (default-book-title): only add lines for
non-nil fields.
(default-score-title): idem.

* lily/paper-book.cc (book_title): separate function for the book
title.

* scm/page-layout.scm (default-book-title): only account for
markup fields.

* scm/framework-ps.scm: new file. Move high level interface from
output-ps.scm

* scm/framework-tex.scm (dump-line): new file. High level
interface for output (pages, systems, header).

* lily/paper-book.cc (split_string): new function
(output): output multiple formats, i.e. --format=ps,tex