When refreshing MIDI ports, explicitly release existing ports

On ALSA Linux, node-midi input and output objects hold onto resources that
eventually may run out causing the process to terminate. This change to
Flocking makes use of a work around added to a fork of node-midi which
adds a new explicit "release()" method to free the underlying RtMidi (and
corresponding ALSA) resources.

See: justinlatimer/node-midi#118

package.json

@@ -40,7 +40,7 @@
   },
   "optionalDependencies": {
     "speaker": "colinbdclark/node-speaker#mpg123-lower-latency",
-    "midi": "0.9.5"
+    "midi": "simonbates/node-midi#f00909dc1ba82e33fd86d5e52ebd092cab866744"
   },
   "engines": {
     "node": ">=0.10.x"

src/web/midi.js

@@ -389,6 +389,17 @@ var fluid = fluid || require("infusion"),
     };
 
     flock.midi.system.refreshPorts = function (that, access, onPortsAvailable) {
+        // Delete existing RtMidiIn/RtMidiOut instances before refreshing
+        // to avoid running out of ALSA resources
+        // See https://github.com/justinlatimer/node-midi/issues/118
+        fluid.each(that.ports, function (portList) {
+            fluid.each(portList, function (port) {
+                if (port.midi && port.midi.release) {
+                    port.midi.release();
+                }
+            });
+        });
+
         that.ports = flock.midi.getPorts(access);
         onPortsAvailable(that.ports);
     };