vert. spacing: Rename properties (lily, scm). (issue3031041)

[markpolesky]

Reviewers: ,

Message:
Here's a new patch-set for renaming the vertical spacing
grob properties.  But...

I'm kind of going in circles trying to decide where to put
some things:

1) individual alist-key descriptions
2) individual grob-property descriptions
3) non-staff line reference-points

I wanted to move the property descriptions to the IR.  Easy
enough, and this removes clutter from the NR.  Now, the
alist-keys -- currently they're explained via a
cross-reference to the section on the \paper variables.
However, I began to think that a better place for the
alist-key descriptions is at the top of the
axis-group-interface page in the IR (much like the 'details
keys are explained at the top of the beam-interface page).

But it felt weird to refer to "reference points" in the IR
without also explaining them too, so I included the table
explaining that, and now the axis-group-interface page is
looking cluttered.

Furthermore, if I'm going to put alist-key descriptions on
the axis-group-interface page, I really should put them also
on the staff-grouper-interface page, so now things seem even
more cluttered than before.

One thing that may help is a dedicated
vertical-axis-group-interface page, which we don't currently
have.  Shouldn't we add one?

Anyway, this patch set ends up having some duplication:

reference-points are discussed in
  NR 4.4.1 Within-system spacing properties
  IR 3.2.7 axis-group-interface

spacing alist-keys are discussed in
  NR 4.1.2 Flexible vertical dimensions
  IR 3.2.7 axis-group-interface
  IR 3.2.97 staff-grouper-interface

If anyone has a better idea, let me know.

Sorry it's so huge.  There were a gazillion trailing spaces
that got stripped in some of the translated docs, but I
tried to organize this so it's easier to parse.  Also, some
regression tests were renamed, so you may have to 'git add'?
I don't know.

Thanks!
- Mark

Description:
vert. spacing: Rename properties (lily, scm).

Please review this at http://codereview.appspot.com/3031041/

Affected files:
  M Documentation/de/essay/engraving.itely
  M Documentation/de/learning/fundamental.itely
  M Documentation/de/notation/spacing.itely
  M Documentation/es/essay/engraving.itely
  M Documentation/es/learning/fundamental.itely
  M Documentation/es/notation/spacing.itely
  M Documentation/essay/engraving.itely
  M Documentation/fr/essay/engraving.itely
  M Documentation/learning/fundamental.itely
  M Documentation/notation/changing-defaults.itely
  M Documentation/notation/spacing.itely
  M Documentation/snippets/new/adjusting-lyrics-vertical-spacing.ly
  M input/regression/page-breaking-min-distance2.ly
  D input/regression/page-spacing-loose-lines-non-affinity.ly
  A + input/regression/page-spacing-nonstaff-lines-and-markup.ly
  A + input/regression/page-spacing-nonstaff-lines-between-systems.ly
  A + input/regression/page-spacing-nonstaff-lines-between.ly
  A + input/regression/page-spacing-nonstaff-lines-bottom.ly
  A + input/regression/page-spacing-nonstaff-lines-header-padding.ly
  A + input/regression/page-spacing-nonstaff-lines-top.ly
  A input/regression/page-spacing-nonstaff-lines-unrelated.ly
  M input/regression/page-spacing-staff-group-hara-kiri.ly
  M input/regression/page-spacing-stretchability.ly
  M lily/axis-group-interface.cc
  M lily/include/axis-group-interface.hh
  M lily/page-layout-problem.cc
  M lily/staff-grouper-interface.cc
  M ly/engraver-init.ly
  M python/convertrules.py
  M scm/define-grob-properties.scm
  M scm/define-grobs.scm