`ajv dt` now ignores directories named "mothballed".
Improved DurationSelectorCallback.

DurationSelectorCallback.inequality now accepts a tuple of one or more of
None, Exact, More or Less. This allows us to model model the concept of "select
all components whose duration is greater or equal to x".

The change is provisional until a proper DurationInequality class is
implemented, after the current round of score are complete.
Improved formatting of pitched trills.

Trill pitches command are now guaranteed to format after (and only after) any
other command, markup or indicator which formats to the right of a leaf.

This guarantees that markup is printed by LilyPond relative to the real leaf,
rather than consumed by the dummy pitched trill note.