* scm/page-layout.scm (ly:optimal-page-breaks): use new parameters

* scm/page-layout.scm (ly:optimal-page-breaks): use new parameters
to get sane spaces for titles.

* scm/page-layout.scm (ly:optimal-page-breaks): add
betweensystempadding also to fixed distance for the spring.

* lily/beam-concave.cc: new file, with new routines for concave
decisions. There are now two types of concaveness: 1. a sharp
logic decision forcing a beam horizontal, and 2. a number that
measures how concave beams are that are not caught by 1.

This fixes: morgenlied.ly and input/regression/beam-concave.ly