This is an alternative fix to issue 2664. It assigns a "Staff" alias

This is an alternative fix to issue 2664.  It assigns a "Staff" alias
to FretBoards (which is also reasonable for things like
instrumentName, less so for clefs and similar folderol) and generally
uses \set Staff.stringTuning instead of \set stringTuning.  It could
also be applied on top of the other fix on review (of course, with a
different result from running update-with-convert-ly.sh committed).

The advantage of using this commit alone for a fix is consistent use
of Staff.stringTuning.  The disadvantage is that conversions to
versions between 2.15.10 and 2.15.41 will continue being defective.

However, you would still require a post-2.15.41 convert-ly to fix
that, and the conversion results would be less consistent, and the
conversion rule is more complex.  Since it is unlikely that conversion
to the middle of the 2.15 range will be so important in future as to
make people employ a post-2.15.41 convert-ly for that purpose, I lean
towards using this simpler fix on its own.  It also catches problems
more thoroughly than the previous fix.  While it would still do so
when used for sweeping after the other fix, we's get a mixture of
overrides to Staff.stringTuning, FretBoards.stringTuning and
TabStaff.stringTuning.

So barring more convincing arguments, I would likely proceed with
using just _this_ fix on its own.

Commits:

Add Staff alias to FretBoards, let convert-ly set Staff.stringTuning

Run scripts/auxiliar/update-with-convert-ly.sh

[Graham Percival, 2012-07-25 10:25:01]

LGTM