* lily/side-position-interface.cc (out_of_staff): move contents of

* lily/side-position-interface.cc (out_of_staff): move contents of
out_of_staff into aligned_side.

* input/regression/measure-grouping.ly: fix warning.

* lily/side-position-interface.cc: add staff-padding support to
Side_position_interface::aligned_side.

* lily/system-start-delimiter-engraver.cc (process_music): whoops,
one get_property too many.

* flower/include/drul-array.hh (linear_combination): new function
(scale_drul): new function

* lily/beam.cc: use Drul_array<Real> iso. interval, because *=
operations on empty intervals are silly.