ReleaseNotes_3.1.0.txt

Changes since 3.0.1:

All importers/exporters:
    - Regularize invisible vs regular vs missing m21 Barlines.

All importers:
    - Fix handling of 'title' vs. 'movementName'.

All exporters:
    - Fix handling of "play only" MetronomeMarks.
    - Regularize treatment of absoluteY and placement.
    - Handle Grace vs Appoggiatura more carefully.
    - Handle gaps by exporting invisible rests.
    - Obey chordSymbol.writeAsChord during export (ChordSymbol is not yet supported, but
        if .writeAsChord is true, we'll emit the <chord> itself).
    - Fix handling of staves not in any staffGroup.

MEI importer/exporter:
    - Support lyric placement
    - DatePrimitive range edge that is also a range needs to be
        "[date1..date2]", not "date1/date2".
        We can now import both, but export always produces "[date1..date2]".
    - Fix handling of tuplet.bracket and visibility.

MEI importer:
    - Fix timestamp computation (notice meter changes inside layers before computing
        any timestamps in that measure).
    - Allow <space> to be used as a `@startid` or `@endid` in a staff item (e.g. <hairpin>).

MEI exporter:
    - MetronomeMark implicit text no longer emitted in <tempo>.
    - Fix duplicated clefs/keySigs/meterSigs; if you emit in staffdef, don't emit
        again later at start of layer.
    - Actually emit clef/key/timesig changes that aren't at start of measure.
    - `@midi.bpm` must be exported as a string (fixes an MEI export crash).
    - If `@tstamp2` is going to be in a previous measure, don't crash, just put it at the beginning
        of this measure.
    - Add missing `@isodate` for "datePublished".
    - Fix handling of spanners that start and end in different Parts (we were crashing).
    - Emit ornament accidentals only if visible (there is no `@accid.ges` on
        ornamentals, unfortunately, or we would use that for invisible accidentals).
    - MEI hairpins end at start of `@endid`.  Unfortunately, music21 DynamicWedges
        end at _end_ of dw.getLast().  So we can't use dw.getLast() as `@endid`.  Instead
        we now emit a `@tstamp2` at the ending offset of dw.getLast().

Humdrum importer/exporter:
    - Fix handling of OMD that is not Tempo (picked up `!LO:TX:omd:` import support from
        Verovio, then started emitting that in Humdrum export).
    - Support export of non-note-associated (i.e. timestamped) dynamics/directions/tempos
        by adding a voice full of invisible rests, one of which lands at the desired offset.
        This was a Humdrum export feature, but it exposed several Humdrum import bugs that
        got fixed as well.

Humdrum importer:
    - Fix handling of transposing instruments.
    - Fix handling of preferred vs forced placement of dynamics and hairpins.

Tests:
    - Modify all diffall and showdiff tests to report mismatched number of parts before
        diffing to avoid musicdiff exception.
    - Visualize note offset differences (new musicdiff v3.1 feature) in diffall tests.
    - Print out exception information in diffall tests.