* scm/chords-ignatzek.scm: new file.

* scm/chords-ignatzek.scm: new file.

* ly/chord-modifiers-init.ly (ignatzekExceptionMusic): define
standard chord name exceptions.

* scm/translator-property-description.scm (chordNameSeparator):
add property.
(majorSevenSymbol): add property

* lily/translator-scheme.cc (ly:context-properties): new function
(ly:context-parent): new function.
(print_smob): print context name.

* lily/music.cc (ly:get-music-length): new function
(print_smob): don't print properties.

* lily/duration.cc (duration<?): new function

* scm/double-plus-new-chord-name.scm (ignatzek-chord-names):
jazz chords.

* lily/pitch.cc (ly:pitch-diff): new function.

* input/regression/chords-ignatzek.ly: new file.