rtmidi bindings for haxe

This is a native Haxe extension for rtmidi.

It comes with precompiled ndlls for Mac, but it should work with all RTMidi targets (Windows, Mac, Linux).

Both RTMidiIn and RTMidiOut are supported.

To compile the extension:

cd project
haxelib run hxcpp Build.xml -Dmac
haxelib run hxcpp Build.xml -Dwindows
haxelib run hxcpp Build.xml -Dlinux

To use it:

1. Add the haxelib dependency (RTMidi)

2. Some code like:

function callback(msg: Array<Int>) {
  // msg is an array with the MIDI received bytes
}

static public function main() {
  midi = new rtmidi.RTMidiIn();
  if (midi.getPortCount() == 0) return;

  midi.openPort(0);
  midi.setCallback(callback);
  midi.ignoreTypes(false, false, false);
}