* input/regression/beam-single-stem.ly: new file.

* input/regression/beam-single-stem.ly: new file.

* lily/stem.cc (set_beaming): use #f as signaling value for
beamcount 0.

* lily/beam-engraver.cc (typeset_beam): set right bound if unset.

* lily/beam.cc (set_beaming): read clip-edges property.
(calc_direction): don't suicide for single stem.

* lily/beaming-info.cc (best_splitpoint_index): take bool*
argument, remove 1<<15 hack. Remove clip_edges()

* lily/hairpin.cc (print): only do padding for nonmusical bounds