Added primitive midi file BookTunes (poorly integrated with SignTunes and BookTunes in general)
Added section-based BookTune parser (not yet replacing the old parser in all places)
Midi files are now played with a SoftSynth
Midi file synths are now closed... eventually, in an messy fashion
Changed version to 3.1
Put some lipstick on the piggish midi/book editor
Merge branch 'refs/heads/release-3.1'