Fix MIDI track reordering (again)
Fix begin() iterator decrement
Fix empty tuplets when use LH/RH separation
Fix bar subdivision around tuplets
Tests for LH/RH separation
fix #22018: Filename as black text on dark grey difficult to read
Simplify code of MidiTrack and MidiFile classes
fix #22017: "Shortest note in bar" Quantization setting appears two places
Test for MIDI quantization of dotted 4th by 4th
fix #22012: Use words instead of fractions for quantization note values
fix #22022: Heading names for track panel
fix #22013: Quantization menu does not work when it is already selected
Larger buttons for MIDI import panel
Merge pull request #424 from trig-ger/midi_import

Fixes for MIDI import