Change stringTunings entries from semitones to pitches (issue3842041)

[Carl . D . Sorensen]

Reviewers: ,

Message:
Here's a patch that changes stringTunings entries from semitones to
pitches.

This is needed to allow a TabKey grob to be created.

Also defines stringTunings for orchestral strings, and includes a
function to allow the definition of stringTunings using absolute mode
chords.

Please review.

Merry Christmas!

Carl


Description:
Change stringTunings entries from semitones to pitches

This lays the foundation for creating a TabKey grob that lists
the pitches of each string in the tablature.

Create a new file ly/string-tunings-init.ly
  Defines \makeStringTuning, which takes an absolute-mode chord
    as an argument, so stringTunings definitions are more easily
    human-readable.
  Collects all the default tunings from scm/tablatures.scm, and
    defines them using \makeStringTuning.
  Adds tunings for orchestral strings.

Add table documenting predefined string tunings to appendix.

Write convert-ly rule for change.

Apply convert-ly to source tree.

Edit updated source files to comply with standard .ly formatting
guidelines.

Change definition in python/musicexp.py

Update Docs to match new syntax.

Please review this at http://codereview.appspot.com/3842041/

Affected files:
  M Documentation/de/notation/fretted-strings.itely
  M Documentation/es/notation/fretted-strings.itely
  M Documentation/fr/notation/fretted-strings.itely
  A Documentation/included/display-predefined-string-tunings.ly
  M Documentation/notation/fretted-strings.itely
  M input/regression/tablature-letter.ly
  M input/regression/tablature-string-tunings.ly
  M ly/declarations-init.ly
  A ly/string-tunings-init.ly
  M python/convertrules.py
  M python/musicexp.py
  M scm/tablature.scm
  M scm/translation-functions.scm