* scm/define-music-types.scm (music-descriptions): add RepeatTieEvent

* scm/define-music-types.scm (music-descriptions): add RepeatTieEvent

* lily/repeat-tie-engraver.cc (acknowledge_note_head): new file. cut & paste
froum Laissez_vibrer_engraver.

* ly/declarations-init.ly (repeatTie): add \repeatTie

* scm/define-grobs.scm (all-grob-descriptions): add RepeatTie, RepeatTieColumn

* scm/define-grob-properties.scm (all-user-grob-properties): add
head-direction property.

* lily/tie-formatting-problem.cc (from_semi_ties): rename from
from_lv_ties. Take head direction argument.

* lily/semi-tie-column.cc: rename from
laissez-vibrer-tie-column.cc. Rename class too.

* lily/semi-tie.cc: rename from laissez-vibrer-tie.cc. Rename
class too.