Fixes to jazz chord displays (issue 5320074)

[Carl . D . Sorensen]

Reviewers: ,

Message:
I've uploaded Adam's changes for review.

I removed the spacing changes in scm/chord-ignatzek-names.scm awaiting
resolution on .scm indentation.

Description:
Fixes to jazz chord displays

This issue consists of a well-formed series of commits created by Adam
Spiers.

The commits are independent; each commit modifies a different set of
files.
If the complete patch set builds, each of the individual commits should
build.  I have not tested them, but I've read them carefully and judge
that the risk is low enough to review the complete set.

I have removed the .scm file reformatting from this patch set, as
the final definition of our .scm format is not yet agreed upon.
Therefore,
our policy is to leave spacing as is until we have agreed.

Issue 1503 - add support for "altered" jazz chord (super-Locrian)


fix indentation in chord-ignatzek-names.scm


Doc: fix spurious pluralisation typo in Chord name chart appendix


Issue 1503 - add additionalPitchPrefix to allow choice of prefix for
additional pitches in chords.

This was previously "add", e.g. "Cmaj7 add6add9",
but this results in too much clutter and
is rarely used.

Issue 1503 - Allow choice of minor chord modifier.

For example, often it is preferred to use a hyphen
instead of "m". This can now be achieved via:

  \set minorChordModifier = \markup { "-" }

add slashChordSeparator

Issue 1572 and issue 1503 - Allow choice of
chord modifier separator independently of
chord inversion separator, since conventionally
the latter is always a slash (hence the term
"slash chords"), whereas the former seldom
involves slashes.

add some missing chords to the ignatzek regression test


Issue 1503 - Recognise Lydian chords


enlarge half-diminished slashed circle symbol

Please review this at http://codereview.appspot.com/5320074/

Affected files:
  M Documentation/included/chord-names-jazz.ly
  M Documentation/notation/chords.itely
  M Documentation/notation/notation-appendices.itely
  A input/regression/chord-additional-pitch-prefix.ly
  A input/regression/chord-name-minor.ly
  A input/regression/chord-slash-separator.ly
  M input/regression/chords-funky-ignatzek.ly
  M ly/chord-modifiers-init.ly
  M ly/engraver-init.ly
  M scm/chord-ignatzek-names.scm
  M scm/define-context-properties.scm