Merge branch 'master' into topic/master-translation

* master:
  Minor change from mailist.
  Partial fix bug 370.
  Fix from mailist.
  Minor language tweaks.
  Breakable markups with \markuplines.
  page ref and labels fix: add `labels' to System interface.
  format fixes for svg
  use simple-format for stencil.scm
  use fancy-format for ice-9 format
  use ergonomic-simple-format to save memory use
  define and use ergonomic-simple-format
  use simple-format / ly:format in backend-library.scm
  ly:format: fix ~$ support
  don't do expression comparison.
  junk ice-9 format
  explicitly alias format to simple-format
  junk (ice-9 format) in backend
  doc why ice-9 in coverage.scm
  Allow null spacing and padding in vertical spacing: