* lily/paper-column.cc (before_line_breaking): bug fix.

* lily/paper-column.cc (before_line_breaking): bug fix.

* lily/volta-engraver.cc (process_music): do something sensible if
no staffs found.

* scripts/lilypond-book.py (make_pixmap): opps. Do png conversion
only once.

* Documentation/user/refman.itely (Global layout): made section on
global layout, added spacing documentation.

* lily/staff-symbol.cc (brew_molecule): change ragged right for
staff symbols. See comments.