* lily/include/repeated-music.hh (class Repeated_music): change

* lily/include/repeated-music.hh (class Repeated_music): change
into "namespace" class.

* lily/event.cc: remove Key_change_event.

* lily/include/transposed-music.hh (class Transposed_music): remove.

* lily/transposed-music.cc: remove

* lily/include/relative-music.hh: remove.

* lily/include/music-sequence.hh (struct Music_sequence): change
into "namespace" class.

* lily/untransposable-music.cc (Module): remove

* lily/include/un-relativable-music.hh (Module): remove

* lily/include/untransposable-music.hh (Module): remove

* lily/un-relativable-music.cc: remove file.