* lily/parser.yy (command_element): reverse setting of

* lily/parser.yy (command_element): reverse setting of
instrumentTransposition

* lily/pitch.cc (pitch_interval): rename.

* lily/recording-group-engraver.cc (stop_translation_timestep):
remove macrameing of accumulator and set_car/cdr.

* lily/music.cc (transpose): fold Event::transpose() in.

* lily/event.cc: remove Transpose.

* lily/recording-group-engraver.cc: cleanup.

* ly/music-functions-init.ly (displayMusic): add function.