midi2ly: open midi input file in binary mode. Fixes #834.

midi2ly: open midi input file in binary mode.  Fixes #834.

After some GUB python hacking I decided the problem was not in Python
but in midi.c.  Then it was easy, I printed the midi_dump

    midi_dump = midi.parse (str)

in wine and compared that with the Linux one

    wine: ((1, 960), [])
    linux: ((1, 960), [[(0, (255, 88, '\x04\x02\x18\x08')), (0, [..]

and then printed the input STR to that function

    wine: string:>>> MThd