New files: MonoInputDialog.js, MonoInputHandler.js

Split the code which was in MonoInput.js between
the above two files. The MIDI event handling code
is pretty ancient and needs careful checking and
debugging. The dialog code should be final, except
that the dialog's options still have to be collected.
Completed MonoInputDialog.js

MonoInputHandler.init(options) is called with the
options defined in the dialog, which is then no
longer needed.
Currently debugging monoInputHandler.init()

Ordinary performance is working.
for live performances, the code seems correct as
far as monoInputHandler.init() . An error happens
in getPerformersMsPositions()...
Debugged monoInputHandler.init()