* lily/note-column.cc: reformat.

* lily/note-column.cc: reformat.

* lily/rest-collision.cc (calc_positioning_done): fix whole/half
step positioning for note/rest combinations.

* input/regression/rest-note-collision.ly: new file.

* scm/define-grobs.scm (all-grob-descriptions): add
springs-and-rods

* flower/include/std-vector.hh: switch off again.

* VERSION (PATCH_LEVEL): bump to 2.9.18

* flower/include/std-string.hh: idem.

* flower/include/std-vector.hh (_GLIBCXX_DEBUG): set if NDEBUG not set.