* lily/include/scm-hash.hh (class Scheme_hash_table): idem.

* lily/include/scm-hash.hh (class Scheme_hash_table): idem.

* flower/include/interval.hh: rename elem_b to contains

* lily/lyric-extender.cc (brew_molecule): use heads for width, use
minimum-length for short ones, and shorten so collisions with the
next syllable are avoided.

* lily/beam-quanting.cc (score_slopes_dy): add extra points for
near-zero slopes.
Only do DAMPING_DIRECTION_PENALTY for non-horizontal dy