Simple simulation code

Builds a native program on MacOS that runs the NuEVI firmware compiled for x86_64.
Only input is arrow keys for menu buttons for now. Only output is console and display.

Copied some more library files into the simulation folder, and renamed the modified *.cpp files from the libraries to *_sim.cpp.

simulation/src/simmidi.cpp

@@ -0,0 +1,56 @@
+#include <Arduino.h>
+#include "midi.h"
+
+void midiSetChannel(byte __attribute__((unused)) channel){}
+
+byte midiGetChannel(){ return 1; }
+
+void midiSendProgramChange(int __attribute__((unused)) patch)
+{
+
+}
+
+void midiSendControlChange(int __attribute__((unused)) ccParam, int __attribute__((unused)) ccValue)
+{
+
+}
+
+void midiSendNoteOn(byte __attribute__((unused)) note, int __attribute__((unused)) velocity)
+{
+
+}
+
+void midiSendNoteOff(byte __attribute__((unused)) note)
+{
+
+}
+
+void midiSendAfterTouch(byte __attribute__((unused)) value)
+{
+
+}
+
+void midiSendPitchBend(int __attribute__((unused)) value)
+{
+
+}
+
+void midiDiscardInput()
+{
+
+}
+
+void midiReset()
+{
+
+}
+
+void midiPanic()
+{
+    // turn all notes off
+}
+
+void midiInitialize(byte __attribute__((unused)) channel)
+{
+
+}