* scm/define-grobs.scm (all-grob-descriptions): make NonMusicalPaperColumn

	* scm/define-grobs.scm (all-grob-descriptions): make NonMusicalPaperColumn
	page-breakable by default

	* scm/layout-page-layout.scm (space-systems): fix bug where the force isn't
	correctly calculated for a single-system page

	* scm/lily-library.scm (interval-sane?): check that the first number is no
	bigger than the second number

	* lily/simple-spacer.cc (solve): allow compression even when ragged (but we
	acknowledge that we aren't satisfying constraints)

	* lily/hara-kiri-group-spanner.cc (request_suicide): give equal treatment to
	non-Items

	* lily/grob.cc (pure_height): add minimum-Y-extent

	* lily/gourlay-breaking.cc (solve): don't ignore a compression force, even if we're
	ragged

	* lily/constrained-breaking.cc: convert code to use new Matrix class
	(get_best_solution): new function

	* scm/page.scm (make-page-stencil): don't crash if we annotate-layout when there
	is a page with no systems