* scm/define-grobs.scm: purge self-[XY]-offset varialbes, replace

* scm/define-grobs.scm: purge self-[XY]-offset varialbes, replace
with simple-closure.

* lily/self-aligment-interface.cc (set_align_self): new function
(set_center_parent): new function.

* lily/side-position-interface.cc (set_axis): new function.

* lily/new-fingering-engraver.cc (position_scripts): use drul for
generic code.

* scm/define-grob-properties.scm (all-user-grob-properties):
remove [XY]-offset-callbacks add [YX]-offset