I modified kahdeg's midi device by making it faster and more responsive, and
adding the capability to change the instrument and the MIDI channel.  The
10th MIDI channel (#9) is a percussion instrument.

Every input line other than note has defaults and therefore doesn't need to be
connected (you can override defaults by using the component's parameters at
the lower left hand side of the Logisim window).

A note value of 128 plays silence.  I added this feature since note 0 of a
piano (and some other instruments) does actually have a hearable note (or
sound).  This is why the note line is now 8 bits.

midi.jar works in the original Logisim (tested with 2.7.1)
midi-ev.jar works in Logisim Evolution
midi-both.jar works in both, but it's probably best to use the others, unless
    you absolutely want your circuit to work in either Logisim without changes.
kahdeg.jar is the original midi device

Mark Craig
