* lily/grob.cc: remove X-extent-callback / Y-extent-callback.

* lily/grob.cc: remove X-extent-callback / Y-extent-callback.

* scm/define-grob-properties.scm (all-user-grob-properties):
remove callback property.

* lily/include/grob.hh (class Grob): remove property_callbacks_
member. Properties of procedure type are assumed to be callbacks.

* lily/ligature-engraver.cc (override_stencil_callback):
rewrite. Use noteHeadLigaturePrimitive as source.

* scm/define-grob-properties.scm (all-internal-grob-properties):
remove ligature-primitive-callback

* lily/include/dimension-cache.hh (class Dimension_cache): make
class, with Grob as friend.

* lily/grob.cc: remove set_extent_callback(), set_extent() and
has_extent_callback()

* scm/translation-functions.scm (format-new-bass-figure): read
figuredBassPlusDirection

* scm/define-context-properties.scm
(all-user-translation-properties): add figuredBassPlusDirection.

* lily/staff-spacing.cc (next_notes_correction): oops. Init wishes.

* lily/align-interface.cc (set_ordered): new function.

* lily/grob.cc (flush_extent_cache): rewrite.

* lily/dimension-cache.cc (Dimension_cache): cache extent as
Interval pointer directly.

* lily/main.cc (setup_paths): insert extra / .
(setup_paths): junk cff entry.

* lily/font-config.cc (init_fontconfig): only add type1 / otf
directories.

* lily/axis-group-engraver.cc (finalize): remove
extraVerticalExtent, minimumVerticalExtent verticalExtent.

* lily/grob.cc (Grob): don't set extent from ctor.
(extent): use property callbacks.

* lily/axis-group-interface.cc: remove set_axes() function.

* lily/grob-property.cc (del_property): new function.